Polymer electrolyte membrane based on polymer formed from monomer having functional group via spacer structure at high density

Abstract

The present invention provides: a monomer having a functional group via a spacer structure, which monomer is capable of forming a polymer; and the polymer. Provided are: a monomer having a functional group via a spacer structure, which monomer is capable of forming a polymer; and the polymer.

Description

Polymer electrolyte membranes based on polymers formed by polymerization monomers and polymerization that have high density functional groups via spacer structures

[0001] The present invention relates to a polymer electrolyte membrane based on a polymer formed by polymerization of a polymerization monomer having functional groups at high density via a spacer structure.

[0002] Fuel cells, which are expected to be a clean power generation system, generate electrical energy by electrochemically reacting hydrogen and oxygen using the reverse reaction of water electrolysis. In particular, solid polymer fuel cells, which use a polymer electrolyte membrane, are used in fuel cell vehicles and other applications.

[0003] The basic component of a polymer electrolyte fuel cell is a membrane electrode assembly (MEA), which is made by sandwiching a proton-conducting membrane called a polymer electrolyte membrane between gas diffusion electrodes, which consist of a gas diffusion layer and a catalyst layer containing an ionomer.If protons do not move properly in the electrolyte membrane, the fuel cell reaction will not occur, and excellent power generation characteristics (high output) will not be obtained.

[0004] For this reason, it is important to use a polymer electrolyte membrane that exhibits high proton conductivity (for example, 0.1 S / cm or more), and the polymer electrolyte membrane is considered to be one of the most important parts in a fuel cell.

[0005] Currently, the electrolyte membranes used in commercially available fuel cell vehicles and the like are made of perfluorosulfonic acid polymers, such as Nafion® developed by DuPont. By wetting the membrane at 70°C to 90°C, protons move along the water molecules, achieving high proton transport capacity (proton conductivity > 0.1 S / cm).

[0006] Furthermore, by humidifying a chemically crosslinked random copolymer of polystyrene and polystyrene sulfonic acid, which is obtained by sulfonating a chemically crosslinked polystyrene, a proton conductivity of approximately 0.1 S / cm can be achieved if the proportion of polystyrene sulfonic acid is high.

[0007] While the development of polymer electrolyte membranes that exhibit high proton conductivity of 0.1 S / cm or more under such humidified conditions continues, development is also underway for proton-conducting polymer electrolyte membranes that exhibit high proton conductivity of about 0.1 S / cm even without sufficient humidification and insufficient wetting of the membrane.

[0008] Patent Document 1 discloses a polymer electrolyte membrane. The polymer electrolyte membrane of Patent Document 1 includes a polymer having an acidic functional group, and the polymer is (i) a block copolymer having a-b type units in which at least an a block and a b block are linked by a covalent bond, (ii) a chemically crosslinkable polymer having an acidic functional group in a side chain, and / or (iii) a polymer composed of a monomer unit having a phosphonic acid group via a spacer structure, and the polymer does not contain a highly hydrolyzable functional group between the main chain skeleton and the phosphonic acid group.

[0009] The a block of (i) is composed of a hydrophobic polymer or a water-repellent polymer, and the b block of (i) is composed of a polymer having an acidic functional group in a side chain or the polymer of (iii), or the side chain of the b block of (i) is composed of a graft chain containing an acidic functional group in a monomer unit.

[0010] This polymer electrolyte membrane has phosphonic acid and / or phosphonate ester units via a spacer structure, and the membrane does not contain a small molecular weight electrolyte. －３ This polymer electrolyte membrane can be suitably used as a proton conducting membrane in a fuel cell.

[0011] US Pat. No. 5,699,499 discloses the polymerization and copolymerization of monomers containing two acid groups, an aryl group, and two carbons between the acid group and the aryl group.

[0012] Non-Patent Document 1 discloses the synthesis and reactivity of alkyl-1,1,1-trisphosphonate esters. These trisphosphonate esters have three phosphonate ester groups on one carbon atom, and the carbon atom also has a 2-propenyl group (—CH ２ -CH=CH ２) or 5-hexenyl group (—CH ２ -CH ２ -CH ２ -CH ２ -CH=CH ２ ) is attached.

[0013] International Publication WO2023 / 120731A1 International Publication WO2010 / 135167A1

[0014] J. Org. Chem. 2011, 76, 21, 8807-8813

[0015] The present invention provides a novel monomer and polymer that have a functional group via a spacer structure and can constitute a polymer.

[0016] The present invention that achieves the above object is as follows.

[0017] Item 1. A monomer having a functional group via a spacer structure and capable of constituting a polymer, wherein the functional group is a phosphonic acid group and / or a phosphonic acid ester unit; a basic functional group; or a cationic functional group based on a basic functional group; and the spacer structure does not contain a highly hydrolyzable functional group, and each spacer structure has two or more of the phosphonic acid group and / or phosphonic acid ester units; one or more of the basic functional groups; or one or more of the cationic functional groups based on the basic functional group.

[0018] Item 2. The monomer according to Item 1, wherein the functional group is located at an end of the spacer structure.

[0019] Item 3. The monomer according to Item 1, wherein when the functional group is a phosphonic acid group and / or a phosphonate ester unit, the spacer structure is a linear, branched, or cyclic hydrocarbon spacer having 2 to 20 carbon atoms; when the functional group is a basic functional group, the spacer structure is a linear, branched, or cyclic hydrocarbon spacer having 3 to 20 carbon atoms; or when the functional group is a cationic functional group based on a basic functional group, the spacer structure is a linear, branched, or cyclic hydrocarbon spacer having 2 to 20 carbon atoms.

[0020] Item 4. A polymer comprising a monomer unit made of the monomer according to Item 1, wherein the functional group of the monomer unit is a phosphonic acid group and / or a phosphonate ester unit, and the monomer unit has two or more of the phosphonic acid groups and / or phosphonate ester units per spacer structure, the functional group of the monomer unit is a basic functional group, and the monomer unit has one or more of the basic functional groups per spacer structure, or the monomer unit is not a fluorene-based monomer unit, and the functional group is a cationic functional group based on a basic functional group, and the monomer unit has one or more of the cationic functional groups based on a basic functional group per spacer structure.

[0021] Item 5. The polymer according to Item 4, wherein the polymer is a polymer formed by chain polymerization or a polymer formed by step-growth polymerization.

[0022] Item 6. A block polymer in which at least an a block and a b block are linked by a covalent bond, wherein the a block is the polymer according to Item 4, or comprises a monomer unit made of a monomer having a functional group via a spacer structure and capable of constituting a polymer, wherein the functional group of the monomer unit is a phosphonic acid group and / or a phosphonic acid ester unit, the spacer structure does not contain a highly hydrolyzable functional group, and each spacer structure comprises a monomer unit having one phosphonic acid group and / or one phosphonic acid ester unit, and the b block is composed of a hydrophobic polymer or a water-repellent polymer, and is a polymer having a glass transition temperature (Tg) of 50°C or lower.

[0023] Item 7. The block polymer according to Item 6, wherein the b block is a polymer in which an alkyl chain is directly bonded to the main chain skeleton.

[0024] Item 8. The block polymer according to Item 6 or 7, wherein the block polymer is a block polymer in which at least the a block, the b block, and the c block are linked by a covalent bond, and the c block is composed of a hydrophobic polymer or a water-repellent polymer, and is a polymer having a glass transition temperature (Tg) of 120°C or higher.

[0025] Item 9. A polymer electrolyte membrane comprising the polymer according to Item 4 or 5, or the block polymer according to Item 6, 7, or 8.

[0026] Item 10. The polymer electrolyte membrane according to Item 9, which has water resistance.

[0027] Item 11. An ionomer or a membrane / electrode assembly (MEA) comprising the polymer according to item 4 or 5, or the block polymer according to item 6, 7, or 8.

[0028] Item 12. The ionomer or membrane / electrode assembly (MEA) according to Item 11, which has water resistance.

[0029] Item 13. A sheet-like material reinforced membrane comprising the polymer electrolyte membrane according to Item 9 or the ionomer according to Item 11, and reinforced with a sheet-like material having voids.

[0030] Item 14. The sheet material-reinforced membrane according to Item 13, wherein the sheet material having voids is a nonwoven fabric and / or a porous sheet.

[0031] Item 15. A fuel cell including an electrolyte membrane for a fuel cell, a water electrolysis device including an electrolyte membrane for water electrolysis, or an ion exchange device including an ion exchange membrane, which includes the polymer according to item 4 or 5, or the block polymer according to item 6, 7, or 8.

[0032] Item 16. A separation membrane, an anion exchange membrane, or a cation exchange membrane, comprising the polymer according to Item 4 or 5, or the block polymer according to Item 6, 7, or 8.

[0033] The present invention can provide a novel monomer and polymer that have a functional group via a spacer structure and can constitute a polymer.

[0034] Example 1 １ H-NMR spectrum, chain line: p-bromostyrene, dotted line: p-(8-bromooctyl)styrene, dashed line: 8-(p-styryl)-1-octanephosphonic acid diethyl ester, solid line: 8-(p-styryl)-1,1-octanediphosphonic acid tetraethyl ester (Example 1). １３ C-NMR spectrum, chain line: p-bromostyrene, dotted line: p-(8-bromooctyl)styrene, dashed line: 8-(p-styryl)-1-octanephosphonic acid diethyl, solid line: 8-(p-styryl)-1,1-octanediphosphonic acid tetraethyl (Example 1). ３１ P-NMR spectrum, dashed line: 8-(p-styryl)-1-octanephosphonic acid diethyl ester, solid line: 8-(p-styryl)-1,1-octanediphosphonic acid tetraethyl ester (Example 1) １H-NMR spectrum, dashed line: poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate), solid line: sodPA. (Example 1) GPC chromatogram of poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate). Proton conductivity at 100°C, ●: Example 1 (sodPA membrane), ▲: Comparative Example 1 (soPA membrane), ■: Comparative Example 2 (sPA membrane). Proton conductivity at 120°C, ●: Example 1 (sodPA membrane), ▲: Comparative Example 1 (soPA membrane), ■: Comparative Example 2 (sPA membrane). (Example 2) GPC chromatogram of tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate. １ H-NMR spectrum. (Example 2) Tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate １３ C-NMR spectrum. (Example 2) Tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate ３１ P-NMR spectrum (Example 2) １ H-NMR spectrum, dashed line: poly(tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate), solid line: sndPA. (Example 2) GPC chromatogram of poly(tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate). (Example 3) １ H-NMR spectrum, dotted line: p-(4-bromobutyl)styrene, dashed line: 4-(p-styryl)-1-butanephosphonic acid diethyl ester, solid line: 4-(p-styryl)-1,1-butanediphosphonic acid tetraethyl ester (Example 3). １３ C-NMR spectrum, dotted line: p-(4-bromobutyl)styrene, dashed line: 4-(p-styryl)-1-butanephosphonic acid diethyl, solid line: 4-(p-styryl)-1,1-butanediphosphonic acid tetraethyl (Example 3). ３１ P-NMR spectrum, dashed line: 4-(p-styryl)-1-butanephosphonic acid diethyl ester, solid line: 4-(p-styryl)-1,1-butanediphosphonic acid tetraethyl ester (Example 3) １H-NMR spectrum, dashed line: poly(tetraethyl 4-(p-styryl)-1,1-butanediphosphonate), solid line: sbdPA. (Example 3) GPC chromatogram of poly(tetraethyl 4-(p-styryl)-1,1-butanediphosphonate). (Example 4) GPC chromatogram of hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate. １ H-NMR spectrum (Example 4) １ H-NMR spectrum, dashed line: poly(hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate), solid line: sotPA. (Example 4) GPC chromatogram of poly(hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate). (Example 5) GPC chromatogram of p-(9-(p-styryl)-nonyl)pyridine. １ H-NMR spectrum. (Example 5) p-(9-(p-styryl)-nonyl)pyridine １３ C-NMR spectrum. (Example 5) Poly((9-(p-styryl)-1,1-nonanediphosphonic acid tetraisopropyl)-co-(p-(9-(p-styryl)-nonyl)pyridine)) １ H-NMR spectrum. (Example 5) GPC chromatogram of poly((tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate)-co-(p-(9-(p-styryl)-nonyl)pyridine)). (Example 6) GPC chromatogram of 1-ethyl-p-(9-(p-styryl)-nonyl)pyridinium bromide. １ H-NMR spectrum (Example 7) １ H-NMR spectrum, dotted line: so, dashed line: so-soPdE, solid line: so-soPA. (Example 7) GPC chromatogram, dashed line: so, solid line: so-soPdE. (Example 9) Stress-strain curve of sbPA / PPS membrane. (Examples 15-17, Comparative Example 4) Stress-strain curve (Examples 18 and 19) １ H-NMR spectrum, solid line (Example 18): 7,7′-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate), dashed line (Example 19): 2,7-dibromo-9,9-bis(6-bromohexyl)fluorene. (Example 18) １H-NMR spectrum, dashed line: poly(7,7'-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate)), solid line: fb(h ｐ dPA). (Example 18) GPC chromatogram of poly(7,7'-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate)). Proton conductivity at 100°C. ●: Example 18 (fb(h ｐ dPA) membrane) proton conductivity at 120 ° C., ●: Example 18 (fb(h ｐ dPA) film) (comparison sample) 6,6'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(diethyl 1-hexanephosphonate) １ H-NMR spectrum. (Example 19) 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(heptane-1,1-diphosphonic acid tetraisopropyl-1-diethyl phosphonate) １ H-NMR spectrum.

[0035] The present invention will be described in detail below.

[0036] In this specification, the terms "comprise" and "contain" are concepts that encompass all of "comprise," "consist essentially of," and "consist only of."

[0037] In this specification, when a numerical range is expressed as "X to Y", it means X or more and Y or less.

[0038] As used herein, the prefix "poly" refers to a polymer containing two or more monomer units.

[0039] [1] Monomer: The monomer of the present invention is a monomer that has a functional group via a spacer structure and can be used to form a polymer. The monomer is preferably a monomer that can be used to form a polymer by chain polymerization, in which monomer molecules are added one at a time to active sites on a growing polymer chain, or by step polymerization, in which a multifunctional (usually bifunctional) monomer reacts to first form a multifunctional dimer, then a multifunctional trimer, further longer multifunctional oligomers, and finally a multifunctional long-chain polymer.

[0040] (Monomer) The monomer is preferably a chain polymerization monomer capable of forming a polymer by addition polymerization, that is, chain polymerization such as radical polymerization, anionic polymerization, or cationic polymerization.

[0041] The monomer is preferably a monomer for step-growth polymerization that can form a polymer by step-growth polymerization such as condensation polymerization and addition condensation.

[0042] (Monomer for chain polymerization) The monomer is preferably a monomer for chain polymerization that can form, through chain polymerization, a vinyl polymer such as a styrene-based polymer having a monomer unit with a styrene skeleton, or an ethylene-based polymer having a monomer unit with an ethylene skeleton.

[0043] A monomer having a styrene skeleton or a monomer having an ethylene skeleton may have any type of substituent (R) at any position, except for the case where R is a phenyl group in the case of a monomer having an ethylene skeleton.

[0044]

[0045] (Monomer for Sequential Polymerization) The monomer is preferably a monomer for sequential polymerization that can be used to form, through sequential polymerization, a fluorene-based polymer having a monomer having a fluorene skeleton in its monomer unit, a phenylene-based polymer having a monomer having a phenylene skeleton in its monomer unit, a furan-based polymer having a monomer having a furan skeleton in its monomer unit, a thiophene-based polymer having a monomer having a thiophene skeleton in its monomer unit, or the like.

[0046] The monomer having a fluorene skeleton, the monomer having a phenylene skeleton, the monomer having a furan skeleton, and the monomer having a thiophene skeleton may have any type of substituent (R) at any position. １ , X ２ is usually a halogen (Cl, Br, I) or the like.

[0047]

[0048] (Functional Group) The functional group is a phosphonic acid group and / or a phosphonate ester unit; a basic functional group; or a cationic functional group based on a basic functional group.

[0049] (Phosphonic Acid Group and / or Phosphonate Ester Unit) The phosphonic acid group and / or phosphonate ester unit is preferably a functional group composed of at least one member selected from the group consisting of a phosphonic acid group and a phosphonate ester unit.

[0050] The phosphonate ester unit refers to a phosphonate diester unit or a phosphonate monoester unit in which a protecting group is attached to the phosphonic acid group, and particularly refers to a phosphonate diester unit.

[0051] The phosphonic acid group can be easily prepared by deprotecting the phosphonate ester unit.

[0052] The phosphonic acid group and / or phosphonate ester unit is preferably a functional group composed of at least one selected from the group consisting of a phosphonic acid group, a diethyl phosphonate unit, and a diisopropyl phosphonate unit, but is not limited thereto.

[0053] (Basic Functional Group) The basic functional group is preferably a basic functional group composed of at least one selected from the group consisting of an amino group, an imino group, a pyridyl group, an imidazolyl group, a pyrazolyl group, a pyrrolyl group, a pyrimidyl group, a pyrazinyl group, and a triazolyl group, but is not limited thereto as long as it exhibits basicity (the property of accepting a proton or donating an electron pair).

[0054] (Cationic Functional Group Based on Basic Functional Group) A cationic functional group based on a basic functional group is a basic functional group that is quaternized with an organic halogen compound or the like to generate a cation.

[0055] The monomer preferably does not contain a highly hydrolyzable functional group at a position that will become the main chain skeleton of the polymer after polymerization.

[0056] The monomer preferably does not contain a highly hydrolyzable functional group or bond at a position that will become a connecting portion of the main chain skeleton of the polymer after polymerization.

[0057] (Spacer Structure) The spacer structure does not contain a highly hydrolyzable functional group.

[0058] The monomer does not contain a highly hydrolyzable functional group between a portion that will become the main chain skeleton of the polymer after polymerization and the phosphonic acid group and / or phosphonate ester unit, basic functional group, or cationic functional group based on a basic functional group that is part of the side chain of the polymer after polymerization (spacer structure).

[0059] The monomer preferably does not contain a highly hydrolyzable functional group between the part that will become the main chain skeleton of the polymer after polymerization and the spacer structure (the part where the spacer structure is connected to the main chain skeleton, the root part of the side chain), and / or between the phosphonic acid group and / or phosphonate ester unit that is part of the side chain of the polymer after polymerization; the basic functional group; or the cationic functional group based on the basic functional group and the spacer structure.

[0060] The part that becomes the main chain skeleton of the polymer after polymerization is a chain compound (generally a polymer. It may contain not only linear units but also cyclic units), and represents the part that becomes the main chain (corresponding to the center of the chain, trunk). It is also called the main chain skeleton part. In the case of a vinyl monomer, it is generally a vinyl group CH ２ The functional group branching from the main chain skeleton and the unit containing the functional group represent side chains.

[0061] Examples of highly hydrolyzable functional groups include amide bonds, imide bonds, urethane bonds, ester bonds, ether bonds, thioether bonds, thioester bonds, etc. However, the above bonds incorporated into heteroaromatic rings are not considered to be highly hydrolyzable functional groups.

[0062] Each spacer structure has two or more phosphonic acid groups and / or phosphonate ester units; one or more basic functional groups; or one or more cationic functional groups based on a basic functional group.

[0063] The number of phosphonic acid groups and / or phosphonate ester units present via a spacer structure may be, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more per monomer unit.

[0064] The number of basic functional groups present via the spacer structure may be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more per monomer unit.

[0065] The number of cationic functional groups based on basic functional groups present via a spacer structure per monomer unit may be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more.

[0066] The spacer structure is preferably a hydrocarbon spacer, and some and / or all of the hydrogen atoms of the hydrocarbon spacer may be substituted with fluorine.

[0067] In the monomer of the present invention which has a functional group via a spacer structure and can constitute a polymer, preferably, when the functional group is a phosphonic acid group and / or a phosphonate ester unit, the spacer structure is a linear, branched, or cyclic hydrocarbon spacer having 2 to 20 carbon atoms.

[0068] In the monomer of the present invention which has a functional group via a spacer structure and can constitute a polymer, when the functional group is a basic functional group, the spacer structure is preferably a linear, branched, or cyclic hydrocarbon spacer having 3 to 20 carbon atoms.

[0069] In the monomer of the present invention which has a functional group via a spacer structure and can constitute a polymer, when the functional group is a cationic functional group based on a basic functional group, the spacer structure is preferably a linear, branched, or cyclic hydrocarbon spacer having 2 to 20 carbon atoms.

[0070] The monomer preferably has a functional group at the end of the spacer structure. When the spacer structure is linear, the functional group is present at the terminal carbon (one position) of the linear chain. When the spacer structure is branched, the functional group is present at the terminal carbon of the branched chain.

[0071] For example, in the case of a three-branched structure, functional groups are present at the terminal carbon atoms of two of the branched chains, and in the case of a four-branched structure, functional groups are present at the terminal carbon atoms of three of the branched chains. In the case of a cyclic spacer, all carbon atoms that constitute the cyclic spacer and are not directly bonded to the main chain skeleton are considered to be terminal carbons.

[0072] The spacer structure is preferably a hydrocarbon spacer. The spacer structure is preferably a linear, branched, or cyclic hydrocarbon spacer having 2 to 20 carbon atoms. The spacer structure is preferably a methylene (methylene: -CH ２ The number of repeating groups is 2 to 12 (-(CH ２ ) n -units, n=2 to 12).

[0073] When two of the functional groups are bonded to a carbon atom, the spacer is a combination of a methine group (>CH-) and an alkylene (repeated methylene), and when three of the functional groups are bonded to a carbon atom, the spacer is a combination of a tetrasubstituted carbon atom (>C<) and an alkylene; strictly speaking, such a spacer should be called a straight-chain hydrocarbon spacer, but since the main component is alkylene, it will also be called an alkylene spacer.

[0074] The spacer structure is preferably a linear, branched, or cyclic hydrocarbon spacer having 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, or 8 or more carbon atoms, and 20 or less, 19 or less, 18 or less, 17 or less, 16 or less, 15 or less, 14 or less, 13 or less, 12 or less, 11 or less, 10 or less, or 9 or less carbon atoms.

[0075] The spacer structure has a large carbon number, for example, about 6 or more, which makes the polymer less likely to dissolve in water and is useful as an electrolyte membrane. The spacer structure has a small carbon number, for example, about 14 or less, which makes it easy to produce the monomer. The carbon number in the spacer structure is more preferably 7 to 12, and even more preferably 8 to 11.

[0076] The spacer structure preferably contains a monomer having an ethylene skeleton (an alkylene spacer having repeating methylene groups), and is particularly preferably a linear, branched, or cyclic hydrocarbon spacer having 6 or more, 7 or more, or 8 or more carbon atoms and 20 or less, 19 or less, 18 or less, 17 or less, 16 or less, 15 or less, 14 or less, 13 or less, 12 or less, 11 or less, 10 or less, or 9 or less carbon atoms.

[0077] The spacer structure preferably contains a monomer having a styrene skeleton, and is particularly preferably a linear, branched, or cyclic hydrocarbon spacer having 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, or 8 or more carbon atoms, and 20 or less, 19 or less, 18 or less, 17 or less, 16 or less, 15 or less, 14 or less, 13 or less, 12 or less, 11 or less, 10 or less, or 9 or less carbon atoms.

[0078] The spacer structure is preferably a linear, branched, or cyclic hydrocarbon spacer, such as a methylene group, ethylene group, n-propylene group, isopropylene group, n-butylene group, isobutylene group, sec-butylene group, 1-ethylpropylene group, n-pentylene group, isopentylene group, n-hexylene group, isohexylene group, 3-methylpentylene group, n-heptylene group, n-octylene group, n-nonylene group, n-decylene group, n-undecylene group, n-dodecylene group, 5-propylnonylene group, n-tridecylene group, n-tetradecylene group, n-pentadecylene group, hexadecylene group, heptadecylene group, or octadecylene group, or other linear or branched alkylene spacers having 1 to 18 carbon atoms.

[0079] The spacer structure is preferably a cyclic spacer having 3 to 8 carbon atoms, such as a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, or a phenylene group.

[0080] Preferably, the spacer structure may be a combination of a plurality of the structures listed above.

[0081] The spacer structure is preferably bonded to the styrene-based monomer constituting the monomer at any of the o-, m- and p-positions, for example, with a bonding number of 1 to 5.

[0082] [2] Polymer The polymer of the present invention contains a monomer unit composed of a monomer of the present invention that has a functional group via a spacer structure and can constitute a polymer.

[0083] The polymers are preferably polymers formed by step polymerization in which multifunctional (usually difunctional) monomers react to form first multifunctional dimers, then multifunctional trimers, then longer multifunctional oligomers, and finally multifunctional long-chain polymers.

[0084] The polymer is preferably one formed by chain polymerization, in which monomer molecules are added one at a time to active sites on a growing polymer chain.

[0085] The polymer of the present invention is preferably a hydrocarbon-based or hydrogen fluoride-based polymer, more preferably a polymer formed by chain polymerization or a polymer formed by step-growth polymerization. The side chain represents a functional group or a unit containing a functional group branched from the main chain (corresponding to the central part of the chain, trunk).

[0086] The polymer is preferably a polymer formed by addition polymerization, i.e., chain polymerization of radical, anionic, and cationic polymerization, or a polymer formed by condensation polymerization and step-growth polymerization of addition condensation.

[0087] (Polymer formed by chain polymerization) The polymer is preferably a polymer formed by chain polymerization, such as a styrene-based polymer or an ethylene-based polymer.

[0088] (Polymer formed by step-growth polymerization) The polymer is preferably a polymer formed by step-growth polymerization, such as a fluorene-based polymer, a phenylene-based polymer, a furan-based polymer, or a thiophene-based polymer.

[0089] The polymer preferably does not contain a highly hydrolyzable functional group in the main chain.

[0090] The polymer preferably does not contain any highly hydrolyzable functional groups or bonds at the connecting portions of the main chain skeleton.

[0091] The polymer preferably does not contain a highly hydrolyzable functional group between the main chain skeleton and the spacer structure (the portion where the spacer structure is connected to the main chain skeleton, the base portion of the side chain) and / or between the phosphonic acid group and / or phosphonate ester unit that is part of the side chain of the polymer, the basic functional group, or the cationic functional group based on the basic functional group and the spacer structure.

[0092] (Polymer Having Phosphonic Acid Group and / or Phosphonate Ester Unit on Side Chain via Spacer Structure) The polymer includes a monomer unit composed of a monomer, and the functional group of the monomer unit is a phosphonic acid group and / or a phosphonate ester unit, and the monomer unit has two or more of the phosphonic acid group and / or phosphonate ester unit per spacer structure.

[0093] The polymer having a phosphonic acid group and / or a phosphonate ester unit in the side chain is composed of a monomer unit that has a functional group via a spacer structure and can constitute a polymer.

[0094] The polymer may have, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more phosphonic acid groups and / or phosphonate ester units present via a spacer structure per monomer unit.

[0095] The polymer having a phosphonic acid group and / or a phosphonate ester unit in its side chain may be a homopolymer consisting of only monomer units having a phosphonic acid group and / or a phosphonate ester unit via a spacer structure, or a ladandum copolymer consisting of a monomer unit having a phosphonic acid group and / or a phosphonate ester unit via a spacer structure and other monomer units.

[0096] In the case of a random copolymer, the ratio of the monomer units is preferably such that the monomer units having a phosphonic acid group and / or a phosphonate ester unit via a spacer structure are 50 mol % or more.

[0097] Monomer units other than the monomer unit having a phosphonic acid group and / or a phosphonate ester unit via a spacer structure may include a monomer unit having a basic functional group via a spacer structure, a monomer unit having a cationic functional group based on a basic functional group via a spacer structure, and the like.

[0098] A polymer having a phosphonic acid group in a side chain via a spacer structure can be preferably converted to a phosphonic acid group by deprotecting a phosphonate ester unit. For example, when synthesizing a polymer, the polymer is formed in a state in which a protecting group is attached, and then deprotected to form a polymer having a phosphonic acid group.

[0099] A polymer containing a phosphonate ester unit via a spacer structure is polymerized and then deprotected to form a polymer containing a phosphonic acid group, which is an acidic functional group, in the monomer unit. The deprotection rate in the polymer is preferably 50% or more, more preferably 70% or more, even more preferably 90% or more, and particularly preferably 95% or more.

[0100] A polymer having a phosphonic acid group on a side chain via a spacer structure preferably does not contain a highly hydrolyzable functional group between the main chain skeleton of the polymer and the phosphonic acid group (spacer structure).

[0101] (Polymer Having a Basic Functional Group on a Side Chain via a Spacer Structure) The polymer includes a monomer unit composed of a monomer, and the functional group of the monomer unit is a basic functional group, and the monomer unit has one or more basic functional groups per spacer structure.

[0102] The polymer having a basic functional group in a side chain via a spacer structure is preferably a polymer having a basic functional group composed of at least one selected from the group consisting of an amino group, an imino group, a pyridyl group, an imidazolyl group, a pyrazolyl group, a pyrrolyl group, a pyrimidyl group, a pyrazinyl group, and a triazolyl group, but is not limited to this as long as it exhibits basicity (the property of accepting a proton or donating an electron pair).

[0103] The polymer may have, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more basic functional groups present via a spacer structure per monomer unit.

[0104] The polymer having basic functional groups in its side chains via a spacer structure is preferably a polymer having 5 or more basic functional groups, more preferably 10 or more, and even more preferably 15 or more.

[0105] The molecular weight of the polymer having a basic functional group in a side chain via a spacer structure is preferably 200 or more, 500 or more, or 1,000 or more, and more preferably 2,000 or more, 5,000 or more, 10,000 or more, 20,000 or more, 40,000 or more, or 80,000 or more.

[0106] (Polymer Having a Cationic Functional Group Based on a Basic Functional Group in a Side Chain via a Spacer Structure) The polymer includes a monomer unit made of a monomer, and the monomer unit is not a fluorene-based monomer unit, but the functional group is a cationic functional group based on a basic functional group, and the monomer unit has one or more cationic functional groups based on the basic functional group per spacer structure.

[0107] The polymer having a basic functional group in a side chain via a spacer structure may be a polymer having a cationic functional group based on the basic functional group, or may be a polymer in which a part of the basic functional group has been quaternized with an organic halogen compound to become a cation, thereby forming a cationic functional group based on the basic functional group.

[0108] The polymer may have, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more cationic functional groups based on basic functional groups present via a spacer structure per monomer unit.

[0109] The proportion of cationic functional groups based on basic functional groups among the basic functional groups may be 10 mol % or more, or may be 30 mol %, 50 mol %, 70 mol %, 90 mol %, or 100 mol %.

[0110] An organic halogen compound is, for example, a compound having an alkyl halide moiety.

[0111] As a compound having an alkyl halide moiety, alkyl halides include Cｎ H ２ｎ＋１ -X (n: natural number, X = F, Cl, Br, I) or R-C ｎ H ２ｎ The compound is a compound represented by -X (R: any organic functional group, N: natural number, X=F, Cl, Br, I), and particularly preferably an alkyl halide.

[0112] [3] Block Polymer The polymer of the present invention is preferably a block polymer (a block polymer having a-b type units) in which at least an a block and a b block are connected by a covalent bond. Block polymers also include so-called graft copolymers and star copolymers having a branched structure.

[0113] The polymer of the present invention is preferably a block polymer in which at least an a block, a b block, and a c block are connected by a covalent bond. Block polymers also include so-called graft copolymers and star copolymers having a branched structure.

[0114] (a Block) The a block is a polymer of the present invention having a phosphonic acid group and / or a phosphonate ester unit in a side chain via a spacer structure. The polymer constituting the a block is preferably a hydrocarbon-based polymer, more preferably a polystyrene-based polymer. The a block has a phosphonic acid group in a side chain via a spacer structure, and can exhibit good conductivity.

[0115] The a block preferably includes a monomer unit having the functional group via a spacer structure and composed of a monomer capable of constituting a polymer, wherein the functional group in the monomer unit is a phosphonic acid group and / or a phosphonate ester unit, the spacer structure does not include a highly hydrolyzable functional group, and the polymer has one or more phosphonic acid groups and / or phosphonate ester units per spacer structure.

[0116] The a block preferably includes a monomer unit having the functional group via a spacer structure and consisting of a monomer capable of constituting a polymer, wherein the functional group in the monomer unit is a basic functional group, the spacer structure does not include a highly hydrolyzable functional group, and each spacer structure is a polymer having one or more basic functional groups.

[0117] The a block preferably includes a monomer unit having the functional group via a spacer structure and consisting of a monomer capable of constituting a polymer, the monomer unit being not a fluorene-based monomer unit, the functional group in the monomer unit being a cationic functional group based on a basic functional group, the spacer structure not containing a highly hydrolyzable functional group, and the polymer having one or more cationic functional groups based on the basic functional group per spacer structure.

[0118] The a block may be a homopolymer consisting of only monomer units having a phosphonic acid group and / or a phosphonate ester unit via a spacer structure, or a random copolymer consisting of monomer units having a phosphonic acid group and / or a phosphonate ester unit in a side chain via a spacer structure and other monomer units. In the random copolymer, the abundance ratio of the two or more types of monomer units contained in the polymer is preferably 50 mol % or more of the monomer units having a phosphonic acid group and / or a phosphonate ester unit in a side chain via a spacer structure.

[0119] In the random copolymer, the monomer unit other than the monomer unit having a phosphonic acid group and / or a phosphonate ester unit via a spacer structure may be a monomer unit having a basic functional group via a spacer structure or a monomer unit having a cationic functional group based on a basic functional group via a spacer structure.

[0120] A polymer having a phosphonic acid group and / or a phosphonate ester unit in its side chain via a spacer structure has a phosphonic acid group, and the spacer structure makes it easy for phase separation to occur between the hydrophobic portion consisting of the main chain skeleton portion and the spacer structure and the hydrophilic portion consisting of the phosphonic acid group. Therefore, the phosphonic acid groups tend to be aligned closely together, and compared to when there is no spacer structure, it is easy to form a continuous ion conduction channel (ion conduction path), and good conductivity is exhibited.

[0121] Furthermore, the spacer structure allows the functional groups to move freely, providing a proton conduction mechanism in which the functional groups move while retaining protons, known as the vehicle mechanism. Furthermore, the proton conduction mechanism in which protons hop from one functional group retaining a proton to another functional group, known as the Grotus mechanism, also exists. Because proton conduction is achieved through the vehicle mechanism of the functional groups and the Grotus mechanism between functional groups, the material exhibits good proton conductivity even in the absence of low molecular weight electrolytes such as water molecules or inorganic acids.

[0122]

[0123]

[0124]

[0125] m≧2 R １ R: a polymerizable unit (a vinyl group, a unit having two halogen groups, etc.) １ ': Main chain skeleton of the monomer unit Spacer: Spacer structure R ２ : a protecting group (such as an alkyl group) or H

[0126] R １ R′ represents the main chain skeleton of a monomer unit having a phosphonic acid group and / or a phosphonate ester unit via a spacer structure. １ represents a vinyl group, R １ ' is -CH ２ -CH-. １ represents a p-substituted styrene unit, R １ ' is -CH ２ -CH(C ６ H ４)-.

[0127] The a block preferably contains a monomer unit composed of a monomer that has a functional group via a spacer structure and can constitute a polymer, the functional group of the monomer unit being a phosphonic acid group and / or a phosphonate ester unit, the spacer structure not containing a highly hydrolyzable functional group, and the polymer contains a monomer unit having one or more of the phosphonic acid group and / or phosphonate ester unit per spacer structure.

[0128] (b Block) The b block is composed of a hydrophobic polymer or a water-repellent polymer, and is a polymer having a glass transition temperature (Tg, measured by DSC) of 50° C. or lower. The polymer constituting the b block preferably has a Tg of 35° C. or lower, more preferably 20° C. or lower.

[0129] The b block is preferably a polymer that does not contain highly hydrolyzable functional groups, and is most preferably a polymer in which alkyl chains are directly bonded to the main chain skeleton, such as poly(p-n-alkylstyrene) or poly(di(n-alkyl)fluorene). The number of alkyl chains may be two or more.

[0130] These polymers can be formed by polymerizing monomers such as pn-alkylstyrene and di(n-alkyl)fluorene.

[0131] The alkyl group may be an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, or the like, and the number of carbon atoms in the alkyl group (m+1) is preferably 2 to 20. The molecular weight is preferably 50,000 or more.

[0132]

[0133]

[0134] The b block may be a homopolymer consisting of only a monomer unit in which an alkyl chain is directly bonded to the main chain skeleton, or a raddam copolymer consisting of a monomer unit in which an alkyl chain is directly bonded to the main chain skeleton and other monomer units.

[0135] When the block polymer is formed into a film, the b block appropriately distributes the stress applied to the film, and contributes to the mechanical strength at low temperatures (100° C. or less) and high temperatures (100° C. or more).

[0136] (c Block) The c block is composed of a hydrophobic polymer or a water-repellent polymer, and is a polymer having a glass transition temperature (Tg, measured by DSC) of 120° C. or higher. The polymer constituting the c block preferably has a Tg of 130° C. or higher, more preferably 140° C. or higher.

[0137] The c block may be a homopolymer consisting of a single monomer unit or a ladandum copolymer consisting of two or more types of monomer units.

[0138] When the block polymer is formed into a membrane, the c-block prevents the membrane from flowing, and contributes to mechanical strength at low temperatures (100° C. or less) and high temperatures (100° C. or more).

[0139] The glass transition temperature (Tg) is a value obtained in accordance with JIS K 7121:2012 based on a DSC curve obtained by measurement at a temperature rise rate of 10°C / min.

[0140] When it is difficult to determine the glass transition temperature (Tg) in a DSC curve, the glass transition temperature (Tg) can also be determined as the peak value of the loss tangent (tan δ) in dynamic mechanical analysis (DMA).

[0141] The hydrophobic polymer or water-repellent polymer of the c-block is preferably a hydrophobic hydrocarbon polymer, and the hydrophobic polymer preferably has a molecular weight of 50,000 or more.

[0142] The water-repellent polymer is a polymer that has the property of repelling water droplets when they are dropped onto its surface (water repellency), and the contact angle is preferably 90° or more, and more preferably 100° or more.

[0143] More preferred examples of the hydrophobic or water-repellent hydrocarbon styrene polymer that is the c block include poly(p-phenylstyrene), poly(p-tert-butylstyrene) (glass transition temperature: 150° C. or higher), etc. Also, more preferred examples of the hydrophobic or water-repellent hydrocarbon fluorene polymer that is the c block include polyfluorene, etc.

[0144] The water-repellent polymer of the c-block preferably includes a silicone compound or a fluorinated polymer. Among fluorocarbon vinyl polymers, polyperfluorostyrene, polyperfluoromethylstyrene, etc. are more preferred.

[0145] The average degree of polymerization of the a block, the b block, or the c block is preferably an integer of 2 or more, for example, 2 or more, 10 or more, 30 or more, 50 or more, 100 or more, 200 or more, 500 or more, 800 or more, 1,000 or more, 1,500 or more, or 2,000 or more. The average degree of polymerization of the a block is preferably 20,000 or less, 15,000 or less, 10,000 or less, 8,000 or less, 5,000 or less, or 4,000 or less.

[0146] The average degree of polymerization can be determined by gel permeation chromatography (GPC) using standard polystyrene or by comparing the proton intensity of initiator residues with the proton intensity of the repeating unit of the polymer. １ Determined by H-NMR.

[0147] The molecular weight of the block polymer is preferably 50,000 or more, 100,000 or more, 200,000 or more, 400,000 or more, 600,000 or more, or 800,000 or more.

[0148] The molecular weight of the polymer is determined by gel permeation chromatography (GPC) to determine the molecular weight distribution (Mw / Mn) using polystyrene standards for molecular weight calibration.

[0149] [4] Combination of a polymer having a phosphonic acid group and / or a phosphonate ester unit in the side chain via a spacer structure with a polymer having a basic functional group and / or a cationic functional group based on a basic functional group in the side chain via a spacer structure. A polymer (random polymer or homopolymer) containing a monomer unit having a phosphonic acid group and / or a phosphonate ester unit via a spacer structure may be combined with a polymer (random polymer or homopolymer) containing a monomer unit having a basic group and / or a cationic functional group based on a basic functional group via a spacer structure. The combination can be achieved by mixing or copolymerization.

[0150]

[0151] Z: basic functional group

[0152] A polymer having a basic functional group in a side chain via a spacer structure contains Z (basic functional group). In a homopolymer, random copolymer, or block polymer having a basic functional group in a side chain via a spacer structure, Z (basic functional group) represents a basic functional group, such as an amino group, imino group, pyridyl group, imidazoyl group, pyrazolyl group, pyrrolyl group, pyrimidyl group, pyrazinyl group, or triazolyl group.

[0153]

[0154] (+)Z-R: Cationic functional group based on a basic functional group X(-): Counter anion of the cationic functional group

[0155] The polymer having a basic functional group and / or a cationic functional group based on a basic functional group in a side chain via a spacer structure may contain a monomer unit having a basic functional group and a cationic functional group ((+)Z-R) via a spacer structure.

[0156]

[0157] (P.O. ３ H) (-) (+) Z-R: an ion pair consisting of a phosphonate group and a cationic functional group (PO３ H) (-) (+) Z-H: Acid-base complex consisting of a phosphonic acid group and a basic functional group (an ion pair consisting of the acid and base itself). The volatile acid HX is removed from the system by humidification. n, p, q ≥ 1 m ≥ 2 0 < v, w, x, y ≤ 1 v + w = ​​1

[0158]

[0159] (P.O. ３ H) (-) (+) Z-R: an ion pair consisting of a phosphonate group and a cationic functional group (PO ３ H) (-) (+) Z-H: Acid-base complex consisting of a phosphonic acid group and a basic functional group (an ion pair consisting of the acid and base itself). The volatile acid HX is removed from the system by humidification. n, p, q, r≧1 m≧2 0<v, w, x, y≦1 v+w=1 R ３ : A hydrophobic or water-repellent functional group having a Tg≦50°C

[0160]

[0161] (P.O. ３ H) (-) (+) Z-R: an ion pair consisting of a phosphonate group and a cationic functional group (PO ３ H) (-) (+) Z-H: Acid-base complex consisting of a phosphonic acid group and a basic functional group (an ion pair consisting of the acid and base itself). The volatile acid HX is removed from the system by humidification. n, p, q, r, s≧1 m≧2 0<v, w, x, y≦1 v+w=1 R ４ : a hydrophobic or water-repellent functional group having a Tg≧120°C

[0162] A polymer (random polymer, homopolymer, or block polymer) having a phosphonic acid group and / or a phosphonate ester unit in the side chain via a spacer structure may be combined with a polymer (random polymer, homopolymer, or block polymer) having a basic functional group in the side chain via a spacer structure and a polymer (random polymer, homopolymer, or block polymer) having a cationic functional group in the side chain via a spacer structure. The combination can be achieved by physical mixing or copolymerization. Block polymers also include graft copolymers and star copolymers.

[0163] A pair of a phosphonic acid group and Z (basic functional group) represents an acid-base complex. A free phosphonic acid group that is not paired with Z can ionize protons that contribute to proton conductivity. A Z that is not paired with a phosphonic acid group is a free basic functional group.

[0164] A pair of a phosphonate group and a (+)Z-R (cationic functional group) represents an ion pair. A free phosphonic acid group that is not paired with a (+)Z-R can ionize a proton that contributes to proton conductivity. A (+)Z-R that is not paired with a phosphonic acid group is a free cationic functional group.

[0165] [5] Method for producing a monomer having two or more phosphonic acid groups and / or phosphonate ester units via a spacer structure (1) (A) Monomers for chain polymerization having two phosphonate ester units per spacer structure: tetraethyl 8-(p-styryl)-1,1-octanediphosphonate, tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate, tetraethyl 4-(p-styryl)-1,1-butanediphosphonate, etc.

[0166] (B) Monomers for chain polymerization having three phosphonate ester units per spacer structure: hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate, etc. These can be synthesized by the following steps.

[0167] (Step 1-1 of the first step (A)) Under a nitrogen atmosphere, a monomer such as p-bromostyrene is dissolved in dehydrated tetrahydrofuran (THF) and cooled to -78°C. An n-hexane solution of a polymerization initiator (n-butyllithium, etc.) is added. An alkylene dibromide (1,8-dibromooctane, 1,4-dibromobutane, etc.) is added, the temperature is raised to -40°C, and the mixture is stirred, and then further stirred at room temperature. Thereafter, methanol is added to terminate the reaction, and a monomer having an alkylene spacer (p-(8-bromooctyl)styrene, p-(4-bromobutyl)styrene, etc.) is synthesized.

[0168] (Step 1-2 of the first step (A)) The precursor monomer having an alkylene spacer obtained in step 1-1 (p-(8-bromooctyl)styrene, p-(4-bromobutyl)styrene, etc.) is dissolved in phenylacetonitrile, triethyl phosphite is added, and the mixture is stirred in an oil bath at 120°C. After separation and purification, diethyl 8-(p-styryl)-1-octanephosphonate, diethyl 4-(p-styryl)-1-butanephosphonate, etc. are obtained.

[0169] (Step 1-3 of the first step (A)) Tetraethyl 8-(p-styryl)-1,1-octanediphosphonate, tetraethyl 4-(p-styryl)-1,1-butanediphosphonate, etc. are synthesized.

[0170] Under an argon atmosphere, diethyl 8-(p-styryl)-1-octanephosphonate, diethyl 4-(p-styryl)-1-butanephosphonate, etc. are dissolved in dehydrated THF and cooled to -78°C. A THF / heptane / ethylbenzene solution of lithium diisopropylamide (LDA) is added to the solution and stirred. Diethyl chlorophosphate is added to the solution and stirred for a while, and then the solution is stirred at room temperature. Chain polymerization monomers (tetraethyl 8-(p-styryl)-1,1-octanediphosphonate, tetraethyl 4-(p-styryl)-1,1-butanediphosphonate) having two phosphonate ester units per spacer via alkylene spacers are obtained.

[0171] (First Step (B)) Sodium hydride dispersed in liquid paraffin is dissolved in dehydrated THF under a nitrogen atmosphere, and tetraisopropyl methylenediphosphonate is added. Thereafter, a monomer having an alkylene spacer (e.g., p-(8-bromooctyl)styrene) is added, and the mixture is stirred at 70°C and further stirred at 55°C. After separation and purification, a monomer for chain polymerization (e.g., tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate) having two phosphonate ester units per spacer via the alkylene spacer is obtained.

[0172] (First Step (C)) A chain polymerization monomer having two phosphonate ester units per spacer (e.g., tetraethyl 8-(p-styryl)-1,1-octanediphosphonate) is dissolved in dehydrated THF under a nitrogen atmosphere and cooled to 0°C. A THF solution of sodium bis(trimethylsilyl)amide is added to the solution and stirred. Diethyl chlorophosphite is added to the solution and stirred, and aqueous hydrogen peroxide is added and further stirred to obtain a chain polymerization monomer having three phosphonate ester units per spacer (e.g., hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate).

[0173] After the first step, the volatile solvent is evaporated by rotary evaporation, followed by extraction by a liquid separation operation to remove the solvent, and then by vacuum distillation to remove unreacted raw material compounds and by-products.

[0174]

[0175] (2) (A) Monomers for sequential polymerization having two phosphonate ester units per spacer structure: 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate), etc.

[0176] (B) Monomers for sequential polymerization having three phosphonate ester units per spacer structure: 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(heptane-1,1-diphosphonic acid tetraisopropyl-1-diethyl phosphonate), etc. These can be synthesized by the following steps, etc.

[0177] (1 of the first step): Sodium hydride (concentration 60 wt%) dispersed in liquid paraffin is dissolved in dehydrated THF under a nitrogen atmosphere, and tetraisopropyl methylenediphosphonate is added. Then, a precursor monomer (2,7-dibromo-9,9-bis(6-bromohexyl)fluorene, etc.) is added, and the mixture is heated and stirred. A saturated aqueous solution of ammonium chloride is then added to terminate the reaction.

[0178] Extraction is performed by a separation operation, and the solvent used in the separation operation is removed using rotary evaporation. Further separation and purification are carried out by passing through a silica gel column to obtain a monomer for sequential polymerization (e.g., 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate)) having two phosphonate ester units per spacer structure. Ethyl acetate and 2-propanol are used as developing solvents.

[0179] (First step 2): In the first step 1, a monomer for sequential polymerization (e.g., 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate) having two phosphonate ester units per spacer structure synthesized is dissolved in dehydrated THF under an argon gas atmosphere and cooled to 0°C.

[0180] A THF solution of sodium bis(trimethylsilyl)amide is added, followed by the addition of diethyl chlorophosphite and then the addition of hydrogen peroxide solution, followed by stirring to synthesize a monomer for sequential polymerization (e.g., 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(heptane-1,1-diphosphonic acid tetraisopropyl-1-diethyl phosphonate)) having three phosphonate ester units per spacer structure.

[0181] The volatile solvent (THF) is evaporated by rotary evaporation. Extraction is performed by a separation operation, and the solvent used in the separation operation is removed by rotary evaporation. Further, unreacted diethyl chlorophosphite and by-products are removed by vacuum distillation.

[0182] The resulting liquid is separated and purified by passing it through a silica gel column to obtain a monomer for sequential polymerization (e.g., 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(heptane-1,1-diphosphonic acid tetraisopropyl-1-diethyl phosphonate)) having three phosphonate ester units per spacer structure. Ethyl acetate, methanol, and propanol are used as developing solvents.

[0183]

[0184] [6] Method for producing a monomer having a basic functional group via a spacer structure (1) Monomers for chain polymerization having a basic functional group: p-(9-(p-styryl)-nonyl)pyridine, etc. These can be synthesized by the following steps, etc.

[0185] A compound having a basic functional group (e.g., p-methylpyridine) is dissolved in dehydrated THF and cooled to -80°C. A tetrahydrofuran (THF) / heptane / ethylbenzene solution of a strong base (e.g., lithium diisopropylamide (LDA)) is added to the solution and stirred. A precursor monomer having an alkylene spacer (e.g., p-(8-bromooctyl)styrene) is added and stirred to obtain a chain polymerization monomer having a basic functional group via a spacer structure (e.g., p-(9-(p-styryl)-nonyl)pyridine).

[0186] After the above steps, the volatile solvent is evaporated by rotary evaporation, and extraction is performed by a liquid separation operation to remove the solvent. Furthermore, the resulting liquid is passed through a silica gel column or the like for separation and purification, to obtain a chain polymerization monomer (e.g., p-(9-(p-styryl)-nonyl)pyridine) having a basic functional group via a spacer structure.

[0187]

[0188] (2) Monomers for sequential polymerization having a basic functional group: 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(p-n-heptylpyridine), etc. These can be synthesized by the following steps.

[0189] A compound having a basic functional group (e.g., p-methylpyridine) is dissolved in a dehydrated solvent and cooled. A strong base (e.g., lithium diisopropylamide (LDA)) is added to the solution and stirred. A precursor monomer having an alkylene spacer (e.g., 2,7-dibromo-9,9-bis(6-bromohexyl)fluorene) is added and stirred to obtain a chain polymerization monomer (7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(p-n-heptylpyridine)) having a basic functional group via a spacer structure.

[0190] After the above steps, the volatile solvent is evaporated by rotary evaporation, and extraction is performed by a liquid separation operation to remove the solvent. Furthermore, the obtained liquid is separated and purified by passing it through a silica gel column or the like to obtain a chain polymerization monomer (7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(p-n-heptylpyridine)) having a basic functional group via a spacer structure.

[0191]

[0192] [7] Method for producing a monomer having a cationic functional group based on a basic functional group via a spacer structure (1) Monomers for chain polymerization having a cationic functional group based on a basic functional group: 1-ethyl-4-(9-(p-styryl)-nonyl)pyridinium bromide, etc. These can be synthesized by the following steps, etc.

[0193] A compound having a basic functional group (e.g., p-methylpyridine) is dissolved in dehydrated THF and cooled to -80°C. A tetrahydrofuran (THF) / heptane / ethylbenzene solution of a strong base (e.g., lithium diisopropylamide (LDA)) is added to the solution and stirred. A precursor monomer having an alkylene spacer (e.g., p-(8-bromooctyl)styrene) is added and stirred to obtain a monomer having a basic functional group via a spacer structure (e.g., p-(9-(p-styryl)-nonyl)pyridine).

[0194] An organic halogen compound (bromoethane, etc.) is added to a monomer having a basic functional group via a spacer structure (p-(9-(p-styryl)-nonyl)pyridine, etc.), and the mixture is stirred to quaternize and cationize, thereby obtaining a monomer having a cationic functional group based on the basic functional group via a spacer structure (1-ethyl-4-(9-(p-styryl)-nonyl)pyridinium bromide, etc.), followed by vacuum drying.

[0195]

[0196] The above-mentioned organic halogen compounds (bromoethane, etc.) are compounds having a halogenated alkyl moiety.

[0197] Among the compounds having the above alkyl halide moiety, the alkyl halide is C ｎ H ２ｎ＋１ -X (n: natural number, X=F, Cl, Br, I), and other compounds having an alkyl halide moiety include R-C ｎ H ２ｎ The compound is a compound represented by —X (R: any organic functional group, n: natural number, X=F, Cl, Br, I), and is particularly preferably an alkyl halide.

[0198] (2) Monomers for sequential polymerization having a cationic functional group based on a basic functional group: 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(N-ethyl-p-n-heptylpyridinium bromide), etc. These can be synthesized by the following steps.

[0199] A compound having a basic functional group (e.g., p-methylpyridine) is dissolved in a dehydrated solvent and cooled. A strong base (e.g., lithium diisopropylamide (LDA)) is added to the solution and stirred. A precursor monomer having an alkylene spacer (e.g., 2,7-dibromo-9,9-bis(6-bromohexyl)fluorene) is added and stirred to obtain a monomer for sequential polymerization (e.g., 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(p-n-heptylpyridine)) having a basic functional group via a spacer structure.

[0200] An organic halogen compound (bromoethane, etc.) is added to a monomer having a basic functional group via a spacer structure (7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(p-n-heptylpyridine, etc.), stirred, and quaternized to cationize, thereby obtaining a monomer for sequential polymerization having a cationic functional group based on a basic functional group via a spacer structure (7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(N-ethyl-p-n-heptylpyridinium bromide, etc.), followed by vacuum drying.

[0201]

[0202] The above-mentioned organic halogen compounds (bromoethane, etc.) are compounds having a halogenated alkyl moiety.

[0203] Among the compounds having the above alkyl halide moiety, the alkyl halide is C ｎ H ２ｎ＋１ -X (n: natural number, X=F, Cl, Br, I), and other compounds having an alkyl halide moiety include R-C ｎ H ２ｎ The compound is a compound represented by —X (R: any organic functional group, n: natural number, X=F, Cl, Br, I), and is particularly preferably an alkyl halide.

[0204] [8] Method for Producing Polymer and Block Polymer (1) Method for Producing Polymer Formed by Chain Polymerization and Block Polymer Formed by Chain Polymerization RAFT Agent (Reversible Addition-Fragmentation Chain Transfer Agent) The RAFT agent is preferably a thiocarbonylthio compound such as a dithioester, a dithiocarbamate, a trithiocarbonate, or a xanthate.

[0205] The RAFT agent is preferably 4-[(2-carboxyethylsulfanylthiocarbonyl)sulfanyl]-4-cyanopentanoic acid, 2-{[(2-carboxyethyl)sulfanylthiocarbonyl]sulfanyl}propanoic acid, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, 2-[(dodecylsulfanylthiocarbonyl)sulfanyl]propanoic acid, 2-(dodecylthiocarbonothioylthio)-2-methylpropanoic acid, methyl 2-(dodecylthiocarbonothioylthio)-2-methylpropionate, or the like.

[0206] The RAFT agent is preferably 2-(dodecylthiocarbonothioylthio)propionic acid, 2-(dodecylthiocarbonothioylthio)-2-methylpropanoic acid pentafluorophenyl ester, 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid 3-azido-1-propanol ester, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, methyl 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoate, or N-hydroxysuccinimidyl 2-(dodecylthiocarbonothioylthio)-2-methylpropionate.

[0207] The RAFT agent is preferably 3-[[(benzylthio)carbonothioyl]thio]propionic acid, 2-cyano-2-propyldodecyltrithiocarbonate, 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid, cyanomethyl[3-(trimethoxysilyl)propyl]trithiocarbonate, 3-butenyl-2-(dodecylthiocarbonothioylthio)-2-methylpropane, phthalimidomethylbutyltrithiocarbonate, 2-(2-carboxyethylsulfanylthiocarbonylsulfanyl)propionic acid, 4-((((2-carboxyethyl)thio)carbonothioyl)thio)-4-cyanopentanoic acid, or the like.

[0208] The RAFT agent is preferably 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanol, cyanomethyl dodecyl trithiocarbonate 1,4-phenylenebis(methylene)didodecylbis(carbonotrithioate), 1,4-phenylenebis(methylene)dibutylbis(carbonotrithioate), 1,4-phenylenebis(methylene)dioctadecylbis(carbonotrithioate), or the like.

[0209] By appropriately selecting the RAFT agent, polymers can be synthesized by radical polymerization.

[0210] Polymerization Initiator The polymerization initiator is preferably an azo-based radical polymerization initiator, a peroxide-based radical polymerization initiator, or the like.

[0211] The polymerization initiator is preferably an azo-based radical polymerization initiator such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), or dimethyl 2,2'-azobisisobutyrate.

[0212] The polymerization initiator is preferably a peroxide radical polymerization initiator such as benzoyl peroxide, t-butyl hydroperoxide, or cumene hydroperoxide.

[0213] The method for synthesizing the polymer and block polymer is not particularly limited as long as it is addition polymerization such as anionic polymerization, cationic polymerization, radical polymerization, etc. Depending on the type of monomer, synthesis may also be performed by condensation polymerization.

[0214] The following describes an example of a method for synthesizing a block polymer having an a block and a b block.

[0215] (A) Step of synthesizing a hydrophobic polymer and producing a b block A monomer constituting the b block (for example, a 4-alkylstyrene monomer), a RAFT agent (a reversible addition-fragmentation chain transfer agent), and a polymerization initiator are mixed and polymerized, and then the resulting mixture is isolated and purified by reprecipitation or the like to synthesize a macro RAFT agent containing the b block.

[0216] The solvent used for synthesis and isolation is preferably a solvent that evaporates relatively easily. Examples of the solvent include water, alcoholic solvents such as methanol and ethanol, and ether solvents such as dimethyl ether, diethyl ether and tetrahydrofuran. The solvent is not limited to these.

[0217] The means for removing the solvent is not particularly limited. The means for removing the solvent is preferably evaporation at room temperature or by heating. The means for removing the solvent may include an appropriate operation such as drying.

[0218] (B) A step of polymerizing a monomer having a phosphonic acid group protected by a protecting group via a spacer structure onto the b block to form an a block, thereby producing a block polymer having a-b type units in which the b block and the a block formed by polymerization of units of the monomer are linked by a covalent bond. Next, in the presence of a polymerization initiator, a macro RAFT agent containing the b block and a monomer (e.g., tetraethyl 8-(p-styryl)-1,1-octanediphosphonate) in which the phosphonic acid group constituting the a block has a protecting group (e.g., ethyl group) are polymerized to produce a block copolymer having a-b type units in which the a block and b block are linked by a covalent bond.

[0219] The solvent used in the synthesis, isolation, and purification is preferably a solvent that evaporates relatively easily. Examples of the solvent include water, alcoholic solvents such as methanol and ethanol, and etheric solvents such as dimethyl ether, diethyl ether, and tetrahydrofuran. The solvent is not limited to these.

[0220] The means for removing the solvent is not particularly limited. The means for removing the solvent is preferably evaporation at room temperature or by heating. The means for removing the solvent may include an appropriate operation such as drying.

[0221] (C) A step of deprotecting the protecting group of the a block to produce a block polymer containing approximately 2.0 or more phosphonic acid groups in the monomer units constituting the a block. By deprotecting the protecting group of the a block using a basic solution (e.g., aqueous sodium hydroxide solution) or bromotrimethylsilane (see Tetrahedron Letters 1977, 18, 155-158), a polymer having approximately 2.0 or more phosphonic acid groups per monomer unit is produced if the deprotection rate is approximately 100%.

[0222] The polymer having a phosphonic acid group in the side chain constituting the a block via a spacer structure is more preferably a polymer containing approximately 2.0 or more phosphonic acid groups per monomer unit.

[0223] (2) Method for producing polymers formed by sequential polymerization and block polymers formed by sequential polymerization (A) Synthesis of polymer Bis(1,5-cyclooctadiene)nickel(0), 2,2'-bipyridyl, and 1,5-cyclooctadiene were weighed out and added to N,N-dimethylformamide (DMF) and stirred under heat.

[0224] Toluene is added to a monomer for sequential polymerization (7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate) etc.) having two phosphonate units per spacer structure, and the mixture is stirred.

[0225] The resulting solution is washed with chloroform, hydrochloric acid, pure water, and saturated saline, and then reprecipitated with n-hexane to obtain a purified polymer formed by sequential polymerization (e.g., poly(7,7'-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate))).

[0226] (B) Deprotection of alkyl protecting groups: A polymer (such as poly(7,7'-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate)) formed by stepwise polymerization is dissolved in chloroform, bromotrimethylsilane is added, the mixture is placed in an oil bath at 40°C, and the mixture is stirred overnight.

[0227] The polymer is reacted and dissolved in an excess amount of methanol, and then purified by dialysis using a cellulose dialysis tube and pure water. Finally, the water is evaporated to obtain a polymer formed by step-growth polymerization in which the alkyl protecting groups have been deprotected.

[0228] [9] Polymer Electrolyte Membrane The polymer electrolyte membrane of the present invention contains the polymer or block polymer of the present invention.

[0229] Polymer electrolyte membranes can be produced by, for example, solvent casting, press molding, or the like using polymers or block polymers. For example, a polymer or block polymer is dissolved in a mixed solvent of methanol and acidic water (pH 1 or less). The resulting solution is transferred to a polypropylene container and left to stand overnight at 60°C to evaporate the solvent, producing a cast membrane.

[0230] Formation of Polymer Electrolyte Membrane The polymer electrolyte membrane is preferably formed into a membrane by a casting method, a pressing method, or the like before removing the solvent, or preferably by a hot melt method, or the like.

[0231] The polymer electrolyte membrane can also be used in a medium temperature range of 100°C or higher and 150°C or lower.

[0232] The operating temperature of the polymer electrolyte membrane is the temperature at which the proton conductive membrane is used, and is preferably room temperature or higher, more preferably 50° C. or higher, 60° C. or higher, 70° C. or higher, 80° C. or higher, or 90° C. or higher, and in some cases 100° C. or higher. The operating temperature of the polymer electrolyte membrane is 200° C. or lower, 150° C. or lower, 140° C. or lower, 130° C. or lower, 120° C. or lower, or 110° C. or lower, in some cases.

[0233]

[10] Ionomer and Membrane Electrode Assembly (MEA) The polymer or block polymer of the present invention can be used as an ionomer (proton-conducting polymer) to form a catalyst layer of a polymer electrolyte fuel cell. Furthermore, a membrane electrode assembly (MEA) can be produced by combining an electrolyte membrane, a catalyst layer (ionomer + catalyst), and a gas diffusion layer.

[0234] (Water Resistance) Some of the polymer electrolyte membranes, ionomers, and membrane / electrode assemblies made of the polymer of the present invention may exhibit good water resistance even when immersed in water (for example, at 60°C for 3 hours) because the proportion of hydrophobic moieties is large, that is, because the monomer of the present invention constituting the polymer of the present invention has a functional group via a spacer structure (a linear, branched, or cyclic hydrocarbon spacer having 2 to 20 carbon atoms).

[0235] The water immersion conditions for evaluating the water resistance of a polymer film are, for example, immersion in water at 20°C to 90°C for 1 to 3 hours. Even after such water immersion (for example, immersion in water at 60°C for 3 hours), the weight retention (%) is preferably 90% by weight or more (weight loss (%) is within 10% by weight), more preferably 95% by weight or more (weight loss (%) is within 5% by weight), and even more preferably 99% by weight or more (weight loss (%) is within 1% by weight).

[0236]

[11] Sheet-like material-reinforced membrane The sheet-like material-reinforced membrane of the present invention is reinforced with a sheet-like material having voids, which contains the polymer electrolyte membrane of the present invention or the ionomer of the present invention.

[0237] The porous sheet material is preferably heat-resistant and is a nonwoven fabric and / or a porous sheet (such as polyphenylene sulfide).

[0238]

[12] Fuel cell including electrolyte membrane for fuel cell, water electrolysis device including electrolyte membrane for water electrolysis, and ion exchange device including ion exchange membrane (Fuel cell including electrolyte membrane for fuel cell) A fuel cell including the electrolyte membrane for fuel cell of the present invention includes the polymer (polymer electrolyte membrane) of the present invention or the block polymer (polymer electrolyte membrane) of the present invention.

[0239] The polymer or block polymer exhibits conductivity even at temperatures above 100° C. and low humidity, and can be used in fuel cells, particularly as a polymer electrolyte membrane for solid polymer fuel cells.

[0240] The polymer electrolyte membrane exhibits high proton conductivity even at temperatures of 100° C. or higher without humidification (e.g., 125° C.). The polymer electrolyte membrane can be used in the medium temperature range of 100° C. or higher and 150° C. or lower without humidification, and can be used in fuel cells without humidification.

[0241] The polymer electrolyte membrane can be used, for example, under conditions of 80°C and 60% RH, or 80°C and 80% RH. The polymer electrolyte membrane exhibits conductivity even at low humidity of 100°C or higher, and can be used particularly as a polymer electrolyte membrane for solid polymer fuel cells.

[0242] The fuel cell preferably has a laminate in which a fuel electrode-side separator having a fuel flow channel, a fuel electrode-side catalyst layer, a polymer (polymer electrolyte membrane) or a block polymer (polymer electrolyte membrane), an air electrode-side catalyst layer, and an air electrode-side separator having an air flow channel are laminated in this order.

[0243] The fuel cell preferably has a laminate in which a fuel electrode-side separator having a fuel flow channel, a fuel electrode-side gas diffusion layer, a fuel electrode-side catalyst layer, a polymer (polymer electrolyte membrane) or a block polymer (polymer electrolyte membrane), a cathode-side catalyst layer, a cathode-side gas diffusion layer, and a cathode-side separator having an air flow channel are laminated in this order.

[0244] (Water Electrolysis Device Comprising Electrolyte Membrane for Water Electrolysis) The water electrolysis device comprising the electrolyte membrane for water electrolysis of the present invention comprises the polymer of the present invention or the block polymer of the present invention. The polymer (polymer electrolyte membrane) or the block polymer (polymer electrolyte membrane) is useful as an anhydrous electrolyte membrane.

[0245] (Ion Exchange Device Comprising Ion Exchange Membrane) An ion exchange device comprising the ion exchange membrane of the present invention comprises the polymer (polymer electrolyte membrane) of the present invention or the block polymer (polymer electrolyte membrane) of the present invention.

[0246]

[13] Separation membrane, anion exchange membrane, or cation exchange membrane (separation membrane) The present invention provides a separation technology suited to various applications by using a separation membrane that has selective permeability, allowing only the target substance to pass through, and chemical resistance. The separation membrane of the present invention can be used to produce salt from seawater, recover specific valuables, refine and produce foods such as wine and soy sauce, and produce acids and alkalis from neutral salt wastewater.

[0247] (CO ２ Separation Membrane) The separation membrane of the present invention is preferably ２ The CO separation membrane of the present invention ２ The separation membrane comprises the polymer of the present invention or the block polymer of the present invention. ２ The separation membrane is designed to reduce CO ２ It can be used in CO capture and storage technologies. ２ The separation membrane ２ Permselectivity, and N ２ It has permselectivity and CO ２ / N ２ It has a permselectivity of .

[0248] (Anion Exchange Membrane) The anion exchange membrane of the present invention contains the polymer of the present invention or the block polymer of the present invention.

[0249] Anion exchange membranes are generally formed from an anion exchange resin layer having a substrate sheet serving as a core material, which functions as a reinforcing material, and are widely used in applications such as salt production, desalination, and electrodialysis for producing acids or alkalis from neutral salts, etc. Anion exchange membranes have a reduced shrinkage rate and excellent current efficiency and water permeability.

[0250] (Cation Exchange Membrane) The cation exchange membrane of the present invention contains the polymer of the present invention or the block polymer of the present invention.

[0251] Electrodialysis (ED) is a technique used to concentrate and separate ions in wastewater. ED is a technology for concentrating and desalination of ions using ion exchange membranes. In the concentration process, ions are concentrated by moving them, making it particularly effective for separating and concentrating membrane foulants and specific trace ions. Cation exchange membranes have excellent selective permeability for specific cations, allowing them to selectively concentrate specific cations, and also have low membrane resistance.

[0252] The present disclosure will be described in more detail below with reference to examples.

[0253] The present disclosure is not limited thereto.

[0254] Example 1 In Example 1, tetraethyl 8-(p-styryl)-1,1-octanediphosphonate was synthesized as a monomer having two phosphonate esters per alkylene spacer in accordance with the following scheme 1 (first step).

[0255]

[0256] Subsequently, this monomer was polymerized according to the following scheme 2 (second step).

[0257]

[0258] The alkyl protecting groups of the obtained poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate) were deprotected to synthesize poly(8-(p-styryl)-1,1-octanediphosphonic acid) (hereinafter also referred to as "sodPA"), which is a polymer having two phosphonic acid groups per spacer via an alkylene spacer (third step).

[0259] This sodPA was formed into a membrane to produce the proton-conductive electrolyte membrane of Example 1 (fourth step).

[0260] (First Step) (Step 1-1) Under a nitrogen atmosphere, 20.9 g (0.159 mol) of p-bromostyrene was dissolved in 340 mL of dehydrated tetrahydrofuran (THF) and cooled to -78°C. 100 mL (0.159 mol) of an n-hexane solution of n-butyllithium (concentration: 1.6 mol / L) was added. 148 mL (218 g, 0.800 mol) of 1,8-dibromooctane was added. Methanol was then added to terminate the reaction, synthesizing p-(8-bromooctyl)styrene.

[0261] The volatile solvents (THF, n-hexane, and methanol) were evaporated by rotary evaporation. Extraction was performed by a separation operation, and the solvent used in the separation operation was removed by rotary evaporation. Furthermore, unreacted 1,8-dibromooctane and by-products were removed by vacuum distillation.

[0262] The liquid obtained after vacuum distillation was dissolved in deuterated chloroform. １ H-NMR measurement was carried out. In Figure 1, the dotted line indicates p-(8-bromooctyl)styrene. １ The H-NMR spectrum is shown in Figure 1. The dashed line indicates p-bromostyrene. １ The H-NMR spectrum is shown.

[0263] The liquid obtained after decompression was dissolved in deuterated chloroform. １３ C-NMR measurements were also carried out. In Figure 2, the dotted line indicates the structure of p-(8-bromooctyl)styrene. １３ The C-NMR spectrum is shown in Figure 2. The dashed line indicates 4-bromostyrene. １３ The C-NMR spectrum is shown.

[0264] The precursor 4-bromostyrene １ In the H-NMR spectrum, protons attached to the vinyl group (a'', b'', c''') were observed at around 5.2, 5.7, and 6.7 ppm, and protons attached to the benzene ring (d'', e''') were observed at around 7.3 and 7.4 ppm.

[0265] After the reaction １ In the H-NMR spectrum, the chemical shifts of the protons (a'', b'', c'') attached to the vinyl group were almost unchanged, and the peaks derived from the protons (d'', e'') attached to the benzene ring shifted to around 7.1 and 7.3 ppm.

[0266] Furthermore, the peak of the methylene group proton (f") adjacent to the benzene ring was observed at 2.6 ppm, the peak of the methylene group proton (m") with a bromo group was observed at 3.4 ppm, and the peaks of the methylene group protons (g") to l") between them were observed at 1.3 to 1.9 ppm. The integral ratio of these peaks was approximately 1:1:6, which suggests that p-(8-bromooctyl)styrene was obtained.

[0267] The peak at 7.27 ppm is a peak derived from chloroform.

[0268] The precursor 4-bromostyrene １３ In the C-NMR spectrum, the carbon atoms of the vinyl group (a''', b''', c''') were observed around 115, 136, and 137 ppm, respectively, and the carbon atoms of the benzene ring (d''', e''', f''') were observed around 132, 128, and 122 ppm, respectively.

[0269] After the reaction １３ In the C-NMR spectrum, the chemical shifts of the protons (a'', b'', c'') attached to the vinyl group shifted to around 113, 137, and 135 ppm, respectively, and the peaks derived from the protons (d'', e'', f'') attached to the benzene ring shifted to around 129, 126, and 143 ppm, respectively. This change in chemical shift is thought to be due to the disappearance of the bromo group attached to the benzene ring.

[0270] Furthermore, eight peaks derived from the carbon atoms (g'' to n'') of the methylene group were newly observed at 28 to 36 ppm, which suggests that p-(8-bromooctyl)styrene was obtained.

[0271] The peak at about 77 ppm is a peak derived from chloroform.

[0272] (Step 1-2) 9.0 g (31 mmol) of p-(8-bromooctyl)styrene obtained in step 1-1 was dissolved in 9.0 g of phenylacetonitrile, and 10.1 g (61.0 mmol) of triethyl phosphite was added, followed by stirring for 12 hours in an oil bath at 120° C. Thereafter, the solvent phenylacetonitrile and unreacted triethyl phosphite were removed by distillation under reduced pressure.

[0273] The resulting liquid was passed through a silica gel column for separation and purification to obtain diethyl 8-(p-styryl)-1-octanephosphonate. The developing solvents used were n-hexane and chloroform.

[0274] The liquid obtained after purification was dissolved in deuterated chloroform. １ In Figure 1, the broken line indicates the structure of diethyl 8-(p-styryl)-1-octanephosphonate. １ The H-NMR spectrum is shown.

[0275] The chemical shifts of the vinyl group, benzene ring, and protons (a' to f') attached to the benzyl position were almost unchanged, while the peak due to the m'' proton of p-(8-bromooctyl)styrene disappeared.

[0276] Furthermore, a new peak derived from the proton (n') of the methylene group next to the oxygen atom of the phosphonate diester appeared at around 4.1 ppm, a peak derived from the proton (o') of the methyl group next to that appeared at 1.3 ppm, and peaks derived from the protons (g' ​​to m') of the methylene group next to the benzyl position to the methylene group next to the phosphorus atom appeared at 1.3 to 1.8 ppm, and the peak integral ratio of f':n':g' to m' + o' was approximately 2:4:20, confirming that 8-(p-styryl)-1-octanephosphonic acid diethyl ester was obtained.

[0277] The peak at 7.27 ppm is a peak derived from chloroform, and the peak at around 0.9 ppm is a peak derived from n-hexane.

[0278] The liquid obtained after purification was dissolved in deuterated chloroform. １３ C-NMR measurement was also carried out. In FIG. 2, the broken line indicates 8-(p-styryl)-1-octanephosphonic acid diethyl ester. １３ The C-NMR spectrum is shown.

[0279] The chemical shifts of the vinyl group and the carbon atoms (a' to f') of the benzene ring were almost unchanged, while the peaks derived from the carbon atoms of the methylene group, indicated as g' to n', shifted in the range of 22 to 36 ppm.

[0280] Furthermore, a new peak derived from the carbon (o') of the methylene group adjacent to the oxygen atom of the phosphonate diester unit appeared at around 61 ppm, and a new peak derived from the proton (p') of the methyl group adjacent to that appeared at around 17 ppm, confirming that 8-(p-styryl)-1-octanephosphonic acid diethyl ester was obtained.

[0281] The peak near 77 ppm is due to chloroform, and the peak near 14 ppm is due to n-hexane.

[0282] The liquid obtained after purification was dissolved in deuterated chloroform and analyzed using an 85% aqueous phosphoric acid solution as an external standard. ３１ In Figure 3, the broken line indicates the P-NMR of diethyl 8-(p-styryl)-1-octanephosphonate. ３１ The P-NMR spectrum is shown.

[0283] The presence of a peak at around 33 ppm attributable to the phosphorus atom (a') of the phosphonate diester is believed to indicate the presence of the target phosphorus compound.These NMR measurement results confirmed that 8-(p-styryl)-1-octanephosphonic acid diethyl ester was obtained.

[0284] (Step 1-3) In the literature (Tetrahedron 2009, 65, 7498-7503 and Polym. Int. 2013, 62, 1717-1728), a compound having an alkylene monophosphonic acid diester structure is reacted with lithium diisopropylamide, and then further reacted with diethyl chlorophosphate to synthesize a compound having an alkylene diphosphonic acid tetraester structure. Based on this reaction, tetraethyl 8-(p-styryl)-1,1-octanediphosphonate was synthesized.

[0285] Specifically, under an argon atmosphere, 6.15 g (17.4 mmol) of diethyl 8-(p-styryl)-1-octanephosphonate was dissolved in 38 mL of dehydrated THF and cooled to -78°C. To this was added 19.5 mL (39.0 mmol) of a THF / heptane / ethylbenzene solution (concentration: 2 mol / L) of lithium diisopropylamide (LDA). To this was added 3.8 mL (4.5 g, 26 mmol) of diethyl chlorophosphate, and the mixture was stirred at room temperature overnight. Thereafter, pure water was added to quench the reaction, synthesizing tetraethyl 8-(p-styryl)-1,1-octanediphosphonate.

[0286] The volatile solvent was evaporated by rotary evaporation. After extraction by liquid separation, the solvent used in the liquid separation was removed by rotary evaporation. Furthermore, unreacted diethyl chlorophosphate and by-products were removed by vacuum distillation.

[0287] The resulting liquid was passed through a silica gel column and an alumina column for separation and purification, yielding tetraethyl 8-(p-styryl)-1,1-octanediphosphonate.

[0288] The developing solvents used were ethyl acetate, methanol, and chloroform.

[0289] The liquid obtained after purification was dissolved in deuterated chloroform. １ In Figure 1, the solid line indicates the tetraethyl 8-(p-styryl)-1,1-octanediphosphonate. １ The H-NMR spectrum is shown.

[0290] The chemical shifts of the vinyl group, benzene ring, and benzyl protons (a to f) remained almost unchanged, while a new peak of the methine group protons (m) next to the two phosphorus atoms appeared at 2.3 ppm.

[0291] Furthermore, a peak derived from the proton (n) of the methylene group next to the oxygen atoms of the two phosphonate diester units was observed at 4.2 ppm, a peak derived from the proton (o) of the methyl group next to that was observed at around 1.3 ppm, and peaks derived from the protons (g to l) of the methylene group two positions away from the phosphorus atom from the methylene group next to the benzyl position were observed at 1.3 to 1.9 ppm. The peak integral ratio of f:m:n:g to l + o was approximately 2:1:8:26, confirming that tetraethyl 8-(p-styryl)-1,1-octanediphosphonate had been obtained.

[0292] The peak at 7.27 ppm is a peak derived from chloroform.

[0293] The liquid obtained after purification was dissolved in deuterated chloroform. １３ C-NMR measurements were also carried out. In Figure 2, the solid line indicates the １３ The C-NMR spectrum is shown.

[0294] The chemical shifts of the vinyl group and the carbon atoms (a to f) of the benzene ring were almost unchanged. On the other hand, the peaks derived from the carbon atoms of the methylene groups g to m shifted in the range of 22 to 35 ppm, and a new peak derived from the carbon atoms of the methine groups adjacent to the two phosphorus atoms appeared near 38 ppm. Furthermore, the peak derived from the carbon atom (o) of the methylene group next to the oxygen atom of the phosphonate diester shifted slightly to near 62 ppm, confirming that tetraethyl 8-(p-styryl)-1,1-octanediphosphonate had been obtained. The peak near 77 ppm is a peak derived from chloroform.

[0295] The liquid obtained after purification was dissolved in deuterated chloroform, and the resulting solution was analyzed using an 85% aqueous phosphoric acid solution as an external standard. ３１ P-NMR measurement was carried out. ３１ The P-NMR spectrum is shown.

[0296] The peak of the phosphorus atom (a') of the phosphonate diester disappeared, and a peak at around 25 ppm derived from the phosphorus atom (a) of the diphosphonate tetraester unit was observed, which suggests the presence of the target phosphorus compound.These NMR measurement results confirmed that tetraethyl 8-(p-styryl)-1,1-octanediphosphonate was obtained.

[0297] (Step 2) 3.02 g (6.18 mmol) of tetraethyl 8-(p-styryl)-1,1-octanediphosphonate obtained in Step 1 was weighed out. 149 μL (2.0 μmol) of a diethylbenzene solution of a reversible addition-fragmentation chain transfer (RAFT) agent (concentration: 5.0 mg / mL) and 18 μL (1.1 μmol) of azobisisobutyronitrile (AIBN) (concentration: 10 mg / mL) were added, respectively, and mixed in a round-bottom flask equipped with a stopcock to prepare a solution.

[0298] The RAFT agent used was 2-(dodecylthiocarbonothioylthio)-2-methylpropanoic acid (DDMAT).

[0299] Nitrogen gas was bubbled through the mixture for 30 minutes, and polymerization was carried out at atmospheric pressure using an oil bath at 120°C while stirring at 500 rpm. After about 4.5 hours, the polymerization reaction was completely stopped by immersing the flask in liquid nitrogen.

[0300] The above reaction solution was dissolved in approximately 10 mL of THF and added dropwise to approximately 100 mL of n-hexane to precipitate an oily polymer (crude poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate)). The resulting polymer was separated by decantation and thoroughly dried under vacuum, and then dissolved again in THF and added dropwise to n-hexane to precipitate the polymer. Unreacted monomers and low-molecular-weight oligomers were removed, and purified poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate) was obtained.

[0301] Using deuterated chloroform, １H-NMR measurement was carried out. １ The H-NMR spectrum is shown by the dashed line.

[0302] The peaks derived from the vinyl group protons disappeared, and broad signals derived from the c' to n' protons were observed at positions similar to the chemical shifts in the monomer, which suggests that a polymer was obtained.

[0303] Poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate) was dissolved in THF to prepare an approximately 0.1% by mass solution, and the molecular weight distribution (Mw / Mn) and number average molecular weight (Mn) were determined by gel permeation chromatography (GPC).

[0304] The GPC chromatogram of poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate) is shown in Figure 5. The Mw / Mn and Mn determined by the molecular weight calibration method using standard polystyrene were 2.03 and 250 kJ, respectively.

[0305] The eluent used was a solvent mainly composed of THF, the flow rate was 1 mL / min, the temperature was 40°C, and the measurement was carried out using two connected TSKgel columns GMHHR-M manufactured by Tosoh Corporation.

[0306] (Third Step) In a literature article (Macromolecules, 2018, 51, 1120-1128.), poly(diethyl p-styrenephosphonate) is reacted with bromotrimethylsilane, then reacted with a methanol solvent, and dialyzed to deprotect the alkyl groups of poly(diethyl p-styrenephosphonate), thereby synthesizing poly(p-styrenephosphonic acid) having no alkylene spacer.

[0307] With reference to this reaction, poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate) obtained in the second step was reacted with bromotrimethylsilane, and then with methanol, followed by dialysis using water to carry out a deprotection reaction.

[0308] Specifically, 1.13 g (2.31 mmol in monomer units) of poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate) was dissolved in 5.0 mL of chloroform, 3.5 g (2.3 mol) of bromotrimethylsilane was added, and the mixture was immersed in a 40°C oil bath and stirred overnight. This solution was concentrated by rotary evaporation, and then reacted and dissolved in an excess amount of methanol. The resulting mixture was transferred to a cellulose dialysis tube and dialyzed against pure water to purify the polymer, and finally, sodPA was obtained by evaporating the water.

[0309] SodPA was dissolved in deuterated methanol. １ In Figure 4, the solid line indicates the H-NMR of poly(8-(p-styryl)-1,1-octanediphosphonic acid). １ The H-NMR spectrum is shown.

[0310] The peak at about 4.2 ppm, which is attributable to the proton of the methylene group adjacent to the oxygen atom of the phosphonate diester, almost disappeared, confirming that deprotection had proceeded to 99%.

[0311] The sharp peak near 3.3 ppm is a peak derived from methanol, and the peak near 4.8 ppm is a peak derived from residual water in the polymer.

[0312] (Fourth step) 50 mg of sodPA was dissolved in approximately 5 g of a mixed solvent of methanol and alkaline water (pH 12). The resulting solution was transferred to a polypropylene container and allowed to stand overnight at 60°C to evaporate the solvent, thereby preparing a cast membrane.

[0313] The obtained cast membrane was immersed in acidic water (pH 1 or less) at 60° C. for 1 hour, and further immersed in pure water at 60° C. for 1 hour. Thereafter, the obtained membrane was heat-pressed at 120° C. for 1 minute to prepare a proton-conducting electrolyte membrane of Example 1.

[0314] <Evaluation> (AC Impedance Measurement) Using a platinum mesh having a thickness of about 0.1 mm as an electrode, AC impedance measurement was carried out on the sample of the proton-conductive electrolyte membrane of Example 1.

[0315] A sample of the proton-conductive electrolyte membrane of Example 1 cut into a strip (thickness: 0.21 mm, width: 0.30 mm, length: 10 mm) was sandwiched between a pair of electrodes arranged opposite each other with an inter-electrode distance of 0.70 cm and an electrode width of 0.22 cm to prepare a measurement cell.

[0316] The measurement cell was placed in a small environmental test chamber (SH-242, manufactured by Espec Corporation) and kept at a temperature of 100°C and a relative humidity of 80% RH (partial pressure of water vapor p Ｈ２Ｏ = 818 hPa), and a potentio / galvanostat VSP-300 (manufactured by BioLogic Science Instruments) was used to adjust the voltage to 50 mV and the frequency to 7 × 10 ６ The AC impedance was measured by changing the frequency in the range of 1 Hz to 1 Hz. The resistance value at the minimum point of the Nyquist plot was read as 4.3 × 10 ３ It was Omega.

[0317] The proton conductivity of this proton-conductive electrolyte membrane sample was calculated using the following formula (1) and was found to be 98 mS / cm (Table 1).

[0318] Proton conductivity = distance between electrodes / (membrane thickness x electrode width x resistance at the minimum point of the Nyquist plot) (1)

[0319] The relative humidity is 60% RH (p Ｈ２Ｏ = 613 hPa), 40% RH (p Ｈ２Ｏ =408hPa), 20%RH (p Ｈ２Ｏ = 204 hPa), and AC impedance measurements were performed. The relative humidity dependence of conductivity at 80°C and 120°C was also measured in the same manner. The membrane of Example 1 exhibited a proton conductivity of 18 mS / cm at 120°C and 30% RH, and 10 mS / cm at 120°C and 20% RH, for example. The conductivity measurement results are summarized in Table 1. In Figures 6 and 7, the conductivities at 100°C and 120°C are represented by filled circles (●), respectively.

[0320] (Water Resistance Evaluation) The weight of the proton-conductive electrolyte membrane of Example 1 was measured before and after immersion in water at 60°C for 3 hours, and the water resistance was evaluated by determining the weight residual ratio (= weight after immersion in water / weight before immersion in water). The weight residual ratio of the proton-conductive electrolyte membrane of Example 1 after immersion in water at 60°C for 3 hours was 99% or more, and the polymer was hardly dissolved in liquid water, demonstrating high water resistance.

[0321] (Durability Evaluation by Fenton Test) 2 ppm of iron (II) sulfate was dissolved in 3.5% hydrogen peroxide solution, and the proton-conductive electrolyte membrane of Example 1 was immersed in the solution and allowed to stand at 80°C for 1 hour. The weights before and after the Fenton test were measured, and the durability was evaluated by calculating the weight retention rate (= weight after Fenton test / weight before Fenton test). The weight retention rate of the proton-conductive electrolyte membrane of Example 1 according to the Fenton test was 97%, indicating high durability.

[0322] Comparative Example 1 In Comparative Example 1, diethyl 8-(p-styryl)-1-octanephosphonate obtained in step 1-2 of Example 1 was used, and the monomers were polymerized and the alkyl protecting groups were deprotected in the same manner as in step 2 and step 3 of Example 1, to synthesize poly(8-(p-styryl)-1-octanephosphonic acid) (hereinafter, also referred to as "soPA"), which is a polymer having one phosphonic acid group per spacer via an alkylene spacer.

[0323] This soPA was made into a membrane in the same manner as in the fourth step of Example 1, to prepare a proton-conductive electrolyte membrane of Comparative Example 1 (hereinafter also referred to as "soPA-1 membrane").

[0324] The proton conductivity of the proton-conducting electrolyte membrane of Comparative Example 1 was measured in the same manner as in Example 1. In Figures 6 and 7 and Table 1, the measurement results of the proton conductivity of Comparative Example 1 at 100°C and 120°C are represented by black triangles (▲), respectively. The membrane of Comparative Example 1 exhibited proton conductivities of, for example, 15 mS / cm at 100°C and 80% RH, 3.8 mS / cm at 120°C and 30% RH, and 2.8 mS / cm at 120°C and 20% RH, and the sodPA membrane of Example 1 exhibited conductivity about 4 to 6 times higher.

[0325] The sodPA membrane of Example 1 has two phosphonic acid groups per monomer via a spacer, resulting in a phosphonic acid group density of 5.3 mmol / g. The soPA-1 membrane of Comparative Example 1 has only one phosphonic acid group per monomer via a spacer, resulting in a phosphonic acid group density of 3.4 mmol / g. The sodPA membrane of Example 1 has a higher acid group density than the soPA-1 membrane of Comparative Example 1, which is thought to be why the sodPA membrane of Example 1 exhibited higher conductivity.

[0326] The water resistance of the proton-conductive electrolyte membrane of Comparative Example 1 was evaluated in the same manner as in Example 1. When the membrane was immersed in water at 60°C for 3 hours, the weight residual rate was 99% or more, and the polymer was hardly dissolved in liquid water, demonstrating high water resistance.

[0327] In the same manner as in Example 1, the Fenton test was carried out on the proton-conductive electrolyte of Comparative Example 1, and the weight retention rate was 99% or more, indicating high durability.

[0328] Comparative Example 2 In Comparative Example 2, poly(p-styrenephosphonic acid) (hereinafter also referred to as "sPA") having no alkyl spacer was synthesized, and AC impedance measurement was carried out in the same manner as in Example 1 to measure its proton conductivity.

[0329] In a literature study (Org. Lett. 2011, 13(8), 2110-2113), p-styrylboronic acid was reacted with diethyl phosphite in the presence of 1,10-phenanthroline and copper(I) oxide as catalysts to synthesize diethyl p-styrenephosphonate. Based on this reaction, diethyl p-styrenephosphonate monomer was synthesized.

[0330] The monomer was purified by passing it through basic alumina. 10 g (0.042 mol), 5.8 mg (0.016 mmol), and 2.6 mg (0.016 mmol) of the purified 4-styrenephosphonic acid diethyl monomer, DDMAT, and AIBN were weighed out and mixed in a round-bottom flask equipped with a stopcock to prepare a solution. Nitrogen gas was then bubbled through the solution for 20 minutes, and polymerization was carried out at atmospheric pressure using an oil bath at 85°C and 500 rpm with stirring. After 1 hour, the polymerization reaction was completely stopped by immersing the flask in liquid nitrogen.

[0331] Approximately 20 mL of THF was added to the reaction solution to prepare an approximately 8% by mass polymer solution. This polymer solution was added dropwise to approximately 300 mL of n-hexane to precipitate a powdery polymer (crude poly(diethyl p-styrenephosphonate)). The resulting polymer was separated by suction filtration and thoroughly dried under vacuum, then re-dissolved in THF and added dropwise to n-hexane to precipitate the polymer. This polymer precipitation process was repeated three times to remove unreacted monomers and low-molecular-weight oligomers, yielding purified poly(diethyl p-styrenephosphonate).

[0332] In the same manner as in Example 1, GPC measurement of poly(diethyl p-styrenephosphonate) was carried out, and the molecular weight was calibrated using standard polystyrene. As a result, the Mw / Mn and Mn of poly(diethyl p-styrenephosphonate) were found to be 1.39 and 280 kJ, respectively.

[0333] In the same manner as in the third step of Example 1, a deprotection reaction of poly(diethyl p-styrenephosphonate) was carried out to obtain sPA.

[0334] Since sPA dissolves in both acidic and alkaline aqueous solutions, 40 mg of sPA was dissolved in 0.8 g of a mixed solution of 1-propanol / acidic aqueous solution (pH 1) = 4 / 6 (weight ratio). The resulting solution was transferred to a polypropylene container and allowed to stand at 60°C for one day to evaporate the solvent, preparing a cast membrane. The resulting membrane was then heat-pressed at 120°C for one minute to prepare a proton-conducting electrolyte membrane of Comparative Example 2.

[0335] The proton conductivity of the proton-conducting electrolyte membrane of Comparative Example 2 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Comparative Example 2 at 100°C and 120°C are summarized in Figures 6 and 7 and Table 1, and are represented by black squares (■), respectively.

[0336] The membrane of Comparative Example 2 exhibited proton conductivities of, for example, 5.8 mS / cm at 100°C and 80% RH, 0.082 mS / cm at 120°C and 30% RH, and 0.027 mS / cm at 120°C and 20% RH. Although the phosphonic acid group densities were similar (phosphonic acid group density of sodPA: 5.3 mmol / g, phosphonic acid group density of sPA: 5.4 mmol / g), the soPA membrane of Example 1 exhibited a conductivity two to three orders of magnitude higher.

[0337] Under highly humidified conditions where a large amount of water molecules are present, it is thought that in both the sodPA membrane of Example 1 and the sPA membrane of Comparative Example 2, water molecules receive protons from phosphonic acid groups, and proton conduction occurs due to proton hopping between water molecules and the movement of water molecules that have received protons.

[0338] On the other hand, when the humidity decreases and the number of water molecules decreases, proton transport by the Grothus and vehicle mechanisms that depend on water molecules becomes difficult to occur, and proton transfer between phosphonic acid groups (Grotus mechanism between phosphonic acid groups) and proton transfer accompanying the movement of the phosphonic acid groups themselves (phosphonic acid group vehicle mechanism) must be relied upon.

[0339] However, in the sPA membrane of Comparative Example 2, the phosphonic acid groups are directly linked to the polystyrene main chain, so the degree of freedom of movement of the phosphonic acid groups is low, and therefore proton exchange between phosphonic acid groups is thought to be difficult to occur.

[0340] On the other hand, in the sodPA membrane of Example 1, the phosphonic acid groups are connected via alkylene spacers, so the degree of freedom of movement of the phosphonic acid groups is much higher than in the sPA membrane, and there are two phosphonic acid groups per monomer, so proton transfer (proton hopping) between the phosphonic acid groups is thought to be more likely to occur.

[0341] It is believed that due to such a proton conduction mechanism, the sodPA membrane of Example 1 exhibited higher conductivity than the sPA membrane, especially in the low humidity range, despite having the same level of acid group density as the sPA membrane.

[0342] In the same manner as in Example 1, the proton-conductive electrolyte membrane of Comparative Example 2 was immersed in water at 60°C for 3 hours, and the sPA gradually dissolved in the liquid water. It was eventually completely dissolved to form a homogeneous (transparent) solution, and it was found that, unlike the proton-conductive electrolyte membrane of Example 1, it had almost no water resistance.

[0343] Since phosphonic acid groups are easily ionized into phosphonate anions and protons and exhibit ionic properties, it is believed that phase separation occurred between the hydrophobic portion consisting of the polystyrene main chain skeleton and alkylene spacer and the hydrophilic and ionic phosphonic acid groups within the monomer unit in the sodPA membrane of Example 1. As a result, it is believed that the polymer as a whole was difficult to hydrate, and the sodPA membrane did not dissolve even when immersed in water.

[0344] On the other hand, the sPA of Comparative Example 2 has hydrophilic and ionic phosphonic acid groups directly attached to the polystyrene main chain.

[0345] It is generally known that diblock polymers of equal composition form a nanophase-separated structure (also called a microphase-separated structure) when χN≧10.5 (χ: interaction parameter between blocks, N: overall degree of polymerization of the block polymer). It is believed that, similar to diblock copolymers, phase separation also occurs between the hydrophobic portion of a monomer unit and the hydrophilic, ionic phosphonic acid group when χN exceeds the critical value of 10.5 (Macromolecules 1980, 13, 1602-1617.).

[0346] However, in the sPA of Comparative Example 2, since there is no alkylene spacer like in sodPA, the value corresponding to N is small and χN does not exceed the critical value of 10.5. Therefore, it is thought that a phase separation structure is not formed, resulting in a membrane that is easily dissolved in water.

[0347] Example 2 In Example 2, tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate was synthesized as a monomer having two phosphonate esters per alkylene spacer using p-(8-bromooctyl)styrene synthesized in Step 1-1 of Example 1 according to the following scheme 3 (first step).

[0348]

[0349] Subsequently, this monomer was polymerized according to the following scheme 4 (second step).

[0350]

[0351] The alkyl protecting groups of the obtained poly(tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate) were deprotected to synthesize poly(9-(p-styryl)-1,1-nonanediphosphonic acid) (hereinafter also referred to as "sndPA"), which is a polymer having two phosphonic acid groups per spacer via an alkylene spacer (third step).

[0352] This sndPA was formed into a membrane to produce the proton-conductive electrolyte membrane of Example 2 (fourth step).

[0353] (Step 1) In a literature article (J. Org. Chem. 2011, 76, 8807-8813.), a compound having a bromoalkyl structure is reacted with sodium hydride, and then further reacted with methylene diphosphonic acid tetraester to synthesize a compound having an alkylene diphosphonic acid tetraester structure. Based on this reaction, tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate was synthesized.

[0354] Specifically, 1.50 g (37.5 mmol) of sodium hydride (concentration 60 wt%) dispersed in liquid paraffin was dissolved in 30 mL of dehydrated THF under a nitrogen atmosphere, and 11.7 g (33.9 mmol) of tetraisopropyl methylenediphosphonate was added. Then, 12.0 g (34.1 mmol) of p-(8-bromooctyl)styrene obtained in step 1-1 of Example 1 was added and stirred. Then, a saturated aqueous solution of ammonium chloride was added to terminate the reaction.

[0355] Next, the volatile solvent was evaporated by rotary evaporation, extraction was performed by liquid separation, and the solvent used in the liquid separation was removed again by rotary evaporation. The resulting liquid was separated and purified by passing it through a silica gel column to obtain tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate. The developing solvents used were n-hexane, isopropanol, and chloroform.

[0356] The liquid obtained after purification was dissolved in deuterated chloroform. １ H-NMR measurement was carried out. １ The H-NMR spectrum is shown.

[0357] p-(8-bromooctyl)styrene shown in FIG. １ Compared with the H-NMR spectrum, the chemical shifts of the vinyl group, benzene ring, and protons (a to f) attached to the benzyl position were almost unchanged, while the peak due to the m″ proton of p-(8-bromooctyl)styrene disappeared.

[0358] Furthermore, a new peak derived from the protons (o) of the methine groups adjacent to the oxygen atoms of the two phosphonate diester units appeared at around 4.8 ppm, a new peak derived from the protons (p) of the methyl groups adjacent to the same appeared at around 1.3 ppm, and a new peak derived from the protons (n) of the methine groups adjacent to the two phosphorus atoms appeared at 2.1 ppm.

[0359] Furthermore, peaks for protons (g to m) from the methylene group next to the benzyl position to the methylene group two positions away from the phosphorus atom were observed at 1.3 to 1.9 ppm. The peak integral ratio of f:n:o:g to m+p was approximately 2:1:4:38, confirming that tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate had been obtained.

[0360] The peak at 7.27 ppm is a peak derived from chloroform.

[0361] The liquid obtained after purification was dissolved in deuterated chloroform. １３ C-NMR measurement was also carried out. １３ The C-NMR spectrum is shown.

[0362] p-(8-bromooctyl)styrene shown in FIG. １３ Compared with the C-NMR spectrum, the chemical shifts of the vinyl group and the carbon atoms (a to f) of the benzene ring were almost unchanged, whereas the peaks derived from the carbon atoms of the methylene group (g to n) shifted in the range of 24 to 38 ppm, and a new peak derived from the carbon atoms of the methine group adjacent to the two phosphorus atoms appeared around 39 ppm.

[0363] Furthermore, a peak derived from the carbon (p) of the methine group adjacent to the oxygen atom of the phosphonate diester unit newly appeared at around 71 ppm, confirming that tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate was obtained.

[0364] The peak near 77 ppm is a peak derived from chloroform.

[0365] The liquid obtained after purification was dissolved in deuterated chloroform, and the resulting solution was analyzed using an 85% aqueous phosphoric acid solution as an external standard. ３１ P-NMR measurement was carried out. ３１ The P-NMR spectrum is shown.

[0366] Since only the peaks at around 23 ppm attributable to the phosphorus atoms of the two phosphonate diester units were observed, it is believed that no phosphorus compounds other than the target phosphonate diester were present.These NMR measurement results confirmed that tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate was obtained.

[0367] (Second Step) 1.9 mg (5.22 μmol) and 5.62 g (15.7 mmol) of DDAMT and tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate obtained in the first step were weighed out, respectively, and 11.7 μL (0.56 μmol) of a diethylbenzene solution of AIBN (concentration: 7.3 mg / mL) was added thereto, followed by mixing in a round-bottom flask equipped with a stopcock to prepare a solution.

[0368] Nitrogen gas was then bubbled through the mixture for 25 minutes, and polymerization was carried out at atmospheric pressure using an oil bath at 120° C. while stirring at 500 rpm. After 12 hours, the flask was immersed in liquid nitrogen to completely stop the polymerization reaction.

[0369] The above reaction solution was dissolved in approximately 3 mL of THF and added dropwise to approximately 500 mL of n-hexane to precipitate an oily polymer (crude poly(tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate)). The resulting polymer was separated by decantation and thoroughly dried under vacuum, and then dissolved again in THF and added dropwise to n-hexane to precipitate the polymer. Unreacted monomers and low-molecular-weight oligomers were removed, and purified poly(tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate) was obtained.

[0370] Using deuterated chloroform, １ 1H-NMR measurement was carried out. In FIG. 11, the broken line indicates the poly(9-(p-styryl)-1,1-nonanediphosphonic acid tetraisopropyl) １ The H-NMR spectrum is shown.

[0371] The peaks derived from the vinyl group protons disappeared, and a broad signal derived from the c' to o' protons was observed at a position similar to the chemical shift in the monomer, which suggests that a polymer was obtained.

[0372] GPC measurement of poly(tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate) was carried out in the same manner as in Example 1. The GPC chromatogram of poly(tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate) is shown in FIG. 12. When the molecular weight was calibrated using standard polystyrene, the Mw / Mn and Mn of poly(tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate) were 2.50 and 117 kJ, respectively.

[0373] (Third Step) In the same manner as in the third step of Example 1, the poly(tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate) obtained in the second step was reacted with bromotrimethylsilane, then with methanol, and dialyzed using water to carry out a deprotection reaction.

[0374] Specifically, 1.46 g (4.07 mmol in monomer units) of poly(tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate) was dissolved in 10 mL of chloroform, and 6.23 g (40.7 mmol) of bromotrimethylsilane was added thereto. The mixture was placed in an oil bath at 40°C and stirred overnight.

[0375] The solution was concentrated by rotary evaporation, then reacted and dissolved in excess methanol, and the resulting mixture was transferred to a cellulose dialysis tube and dialyzed against pure water to purify the polymer. Finally, the water was evaporated to obtain sndPA.

[0376] sndPA was dissolved in deuterated methanol, １ H-NMR measurement was performed. In FIG. 11, the solid line indicates the １ The H-NMR spectrum is shown.

[0377] The integral ratio of the signals (c, d) at 5.5 to 7.5 ppm derived from the protons of the benzene ring to the signals (a, b, e to m) at 0.5 to 2.8 ppm derived from other protons was approximately 4:21, which confirmed that the peak (o') derived from the protons of the methyl groups of the two phosphonate diester units had almost disappeared and that deprotection had progressed by 95% or more.

[0378] The sharp peak near 3.3 ppm is a peak derived from methanol, the peak near 4.8 ppm is a peak derived from residual water in the polymer, the peaks near 1.8 and 3.7 ppm are peaks derived from THF, the peaks near 0.9 and 1.3 ppm are peaks derived from n-hexane, and the peak near 2.3 ppm is a peak derived from by-products and impurities of the deprotection reaction.

[0379] (Fourth Step) In the same manner as in the fourth step of Example 1, the proton-conductive electrolyte membrane of Example 3 was prepared by solution casting and heat pressing.

[0380] The proton conductivity of the proton-conductive electrolyte membrane of Example 2 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Example 2 are summarized in Table 1. The membrane of Example 2 exhibited a proton conductivity of 15 mS / cm at 120°C and 40% RH and 7.3 mS / cm at 120°C and 20% RH, for example, and exhibited a higher conductivity than the proton-conductive electrolyte membranes of Comparative Examples 1 and 2.

[0381] The sndPA membrane of Example 2 has two phosphonic acid groups per monomer via a spacer, resulting in a phosphonic acid group density of 5.1 mmol / g. The soPA membrane of Comparative Example 1 has only one phosphonic acid group per monomer via a spacer, resulting in a phosphonic acid group density of 3.4 mmol / g. The sndPA membrane of Example 2 has a higher acid group density than the soPA membrane of Comparative Example 1, which is thought to be why the sndPA membrane of Example 2 exhibited higher conductivity.

[0382] Under highly humidified conditions where a large amount of water molecules are present, it is thought that in both the sndPA membrane of Example 2 and the sPA membrane of Comparative Example 2, water molecules receive protons from phosphonic acid groups, and proton conduction occurs due to proton hopping between water molecules and the movement of water molecules that have received protons.

[0383] On the other hand, when the humidity decreases and the amount of water molecules decreases, proton transport by the Grouthus and vehicle mechanism, which depends on water molecules, becomes difficult to occur, and proton transfer between phosphonic acid groups (Grothus mechanism between phosphonic acid groups) and proton transfer accompanying the movement of the phosphonic acid groups themselves (phosphonic acid group vehicle mechanism) must be relied upon.

[0384] However, in the sPA membrane of Comparative Example 2, the phosphonic acid groups are directly linked to the polystyrene main chain, so the degree of freedom of movement of the phosphonic acid groups is low, and therefore it is thought that proton exchange between phosphonic acid groups is unlikely to occur.

[0385] On the other hand, in the sndPA membrane of Example 2, the phosphonic acid groups are connected via alkylene spacers, so the degree of freedom of movement of the phosphonic acid groups is much higher than in the sPA membrane, and there are two phosphonic acid groups per monomer, so proton transfer (proton hopping) between phosphonic acid groups is thought to be more likely to occur.

[0386] It is believed that due to such a proton conduction mechanism, the sndPA membrane of Example 2 exhibited higher conductivity than the sPA membrane, especially in the low humidity range, despite having a slightly lower acid group density than the sPA membrane (phosphonic acid group density of sndPA: 5.1 mmol / g, phosphonic acid group density of sPA: 5.4 mmol / g).

[0387] Example 3 In Example 3, tetraethyl 4-(p-styryl)-1,1-butanediphosphonate was synthesized as a monomer having two phosphonate ester units per alkylene spacer via an alkylene spacer according to the following scheme 5 (first step).

[0388]

[0389] Subsequently, this monomer was polymerized according to the following scheme 6 (second step).

[0390]

[0391] The alkyl protecting groups of the obtained poly(tetraethyl 4-(p-styryl)-1,1-butanediphosphonate) were deprotected to synthesize poly(4-(p-styryl)-1,1-butanediphosphonic acid) (hereinafter also referred to as "sbdPA"), a polymer having two phosphonic acid groups per spacer via an alkylene spacer (third step).

[0392] (First Step) (Step 1-1) p-(4-Bromobutyl)styrene was synthesized in the same manner as in Step 1-1 of Example 1, except that 1,4-dibromobutane was used instead of 1,8-dibromooctane.

[0393] The purified liquid was dissolved in deuterated chloroform. １ In FIG. 13, the dotted line indicates the structure of p-(4-bromobutyl)styrene. １ The H-NMR spectrum is shown.

[0394] The precursor 4-bromostyrene １ Compared with the H-NMR spectrum (chain line in Figure 1), the chemical shifts of the protons (a'', b'', c'') attached to the vinyl group were almost unchanged, while the peaks derived from the protons (d'' and e'') attached to the benzene ring were shifted to around 7.1 and 7.3 ppm.

[0395] Furthermore, the peak of the methylene group proton (f") adjacent to the benzene ring was observed at 2.6 ppm, the peak of the methylene group proton (i") with a bromo group was observed at 3.4 ppm, and the peaks of the methylene group protons (g"), l") between them were observed at 1.8 and 1.9 ppm. The integral ratio of these peaks was approximately 1:1:1:1, which suggests that p-(4-bromobutyl)styrene was obtained.

[0396] The peak at 7.27 ppm is a peak derived from chloroform.

[0397] The purified liquid was dissolved in deuterated chloroform. １３C-NMR measurements were also carried out. In FIG. 14, the dotted line indicates the １３ The C-NMR spectrum is shown.

[0398] The precursor p-bromostyrene １３ Compared with the C-NMR spectrum (dotted line in Figure 1), １３ In the C-NMR spectrum, the chemical shifts of the protons (a'', b'', c'') attached to the vinyl group shifted to around 113, 137, and 135 ppm, respectively, and the peaks derived from the protons (d'', e'', f'') attached to the benzene ring shifted to around 129, 126, and 143 ppm, respectively. This change in chemical shift is thought to be due to the loss of the bromo group attached to the benzene ring.

[0399] Furthermore, peaks attributable to the carbon atoms (g'', h'', i'', j'') of the methylene group were newly observed at 30 to 35 ppm, suggesting that p-(4-bromobutyl)styrene was obtained.

[0400] The peak at about 77 ppm is a peak derived from chloroform.

[0401] (Step 1-2) Diethyl 4-(p-styryl)-1-butanephosphonate was synthesized in the same manner as in Step 1-2 of Example 1, except that p-(4-bromobutyl)styrene was used instead of p-(8-bromooctyl)styrene.

[0402] The liquid obtained after purification was dissolved in deuterated chloroform. １ In FIG. 13, the broken line indicates the product of 4-(p-styryl)-1-butanephosphonic acid diethyl ester. １ The H-NMR spectrum is shown.

[0403] The chemical shifts of the vinyl group, benzene ring, and protons (a' to f') attached to the benzyl position were almost unchanged, while the peak due to the i'' proton of p-(4-bromobutyl)styrene disappeared.

[0404] Furthermore, a new peak derived from the proton (n') of the methylene group next to the oxygen atom of the phosphonate diester unit appeared at around 4.1 ppm, a peak derived from the proton (o') of the methyl group next to that appeared at 1.3 ppm, and peaks derived from the protons (g' ​​to m') of the methylene groups next to the benzyl position to the phosphorus atom appeared at 1.3 to 1.8 ppm, and the peak integral ratio of f':n':g' to m' + o' was approximately 2:4:20, confirming that 8-(p-styryl)-1-octanephosphonic acid diethyl ester was obtained.

[0405] The peak at 7.27 ppm is a peak derived from chloroform, and the peak at around 0.9 ppm is a peak derived from n-hexane.

[0406] Furthermore, a new peak derived from the proton (j') of the methylene group next to the oxygen atom of the phosphonate diester appeared at around 4.1 ppm, and a peak derived from the proton (k') of the methyl group next to that appeared at around 1.3 ppm. Peaks derived from the proton (g') attached to the methylene group next to the benzyl position, the proton (h') of the adjacent methylene group, and the proton (i') of the methylene group next to the phosphorus atom were observed at 1.6 to 1.8 ppm, and the peak integral ratio of f':g' to i':j':k' was approximately 2:6:4:6, confirming that 4-(p-styryl)-1-butanephosphonic acid diethyl ester was obtained.

[0407] The peak at 7.27 ppm is a peak derived from chloroform.

[0408] The liquid obtained after purification was dissolved in deuterated chloroform. １３ C-NMR measurement was also carried out. In FIG. 14, the broken line indicates the １３ The C-NMR spectrum is shown.

[0409] The chemical shifts of the vinyl group and the carbon atoms (a' to f') of the benzene ring were almost unchanged, while the peaks derived from the carbon atoms of the methylene group, indicated as g' to j', shifted in the range of 22 to 36 ppm.

[0410] Furthermore, a new peak derived from the carbon (k') of the methylene group adjacent to the oxygen atom of the phosphonate diester unit appeared at around 61 ppm, and a new peak derived from the proton (l') of the methyl group adjacent to that appeared at around 17 ppm, confirming that 4-(p-styryl)-1-butanephosphonic acid diethyl ester was obtained.

[0411] The peak near 77 ppm is a peak derived from chloroform.

[0412] The liquid obtained after purification was dissolved in deuterated chloroform, and 85% aqueous phosphoric acid solution was used as an external standard. ３１ In FIG. 15, the broken line indicates the product of 4-(p-styryl)-1-butanephosphonic acid diethyl ester. ３１ The P-NMR spectrum is shown.

[0413] The presence of a peak at around 33 ppm attributable to the phosphorus atom (a') of the phosphonate diester unit is believed to indicate the presence of the target phosphorus compound.These NMR measurement results confirmed that 4-(p-styryl)-1-butanephosphonic acid diethyl ester was obtained.

[0414] (Step 1-3) Tetraethyl 4-(p-styryl)-1,1-butanediphosphonate was synthesized in the same manner as in Step 1-3 of Example 1, except that diethyl 4-(p-styryl)-1-butanephosphonate was used instead of diethyl 8-(p-styryl)-1-octanephosphonate.

[0415] The liquid obtained after purification was dissolved in deuterated chloroform. １ In FIG. 13, the solid line indicates the tetraethyl 4-(p-styryl)-1,1-butanediphosphonate. １ The H-NMR spectrum is shown.

[0416] The chemical shifts of the vinyl group, benzene ring, and benzyl protons (a to f) were almost unchanged, while a new peak of the methine group proton (i) next to the two phosphorus atoms appeared at 2.3 ppm.

[0417] Furthermore, a peak derived from the proton (j) of the methylene group next to the oxygen atoms of the two phosphonate diester units was observed at 4.2 ppm, a peak derived from the proton (k) of the methyl group next to that was observed at around 1.3 ppm, and peaks derived from the proton (g) of the methylene group next to the benzyl position and the proton (h) of the methylene group two positions away from the phosphorus atom were observed at 1.9 ppm. The peak integral ratio of f:g+h:i:j:k was approximately 2:4:1:8:12, confirming that tetraethyl 4-(p-styryl)-1,1-butanediphosphonate was obtained.

[0418] The peak at 7.27 ppm is a peak derived from chloroform.

[0419] The liquid obtained after purification was dissolved in deuterated chloroform. １３ C-NMR measurement was also carried out. In FIG. 14, the solid line indicates the １３ The C-NMR spectrum is shown.

[0420] The chemical shifts of the vinyl group and the carbon atoms (a to f) of the benzene ring were almost unchanged, whereas the peaks derived from the carbon atoms of the methylene group (g to i) shifted in the range of 25 to 35 ppm, and new peaks derived from the carbon atoms of the methine group adjacent to the two phosphorus atoms appeared at around 38 ppm.

[0421] Furthermore, the peak derived from the carbon (k) of the methylene group next to the oxygen atom of the phosphonate diester was slightly shifted to around 62 ppm, confirming that tetraethyl 4-(p-styryl)-1,1-butanediphosphonate was obtained.

[0422] The peak near 77 ppm is a peak derived from chloroform.

[0423] The liquid obtained after purification was dissolved in deuterated chloroform, and the resulting solution was analyzed using an 85% aqueous phosphoric acid solution as an external standard. ３１ In FIG. 15, the solid line indicates the P-NMR of tetraethyl 4-(p-styryl)-1,1-butanediphosphonate. ３１ The P-NMR spectrum is shown.

[0424] The peak of the phosphorus atom (a') of the phosphonate diester disappeared, and peaks at around 25 ppm derived from the phosphorus atoms (a) of the two phosphonate diester units were observed, which suggests the presence of the target phosphorus compound.These NMR measurement results confirmed that tetraethyl 4-(p-styryl)-1,1-butanediphosphonate was obtained.

[0425] (Second Step) Monomers were polymerized in the same manner as in the second step of Example 1, except that tetraethyl 4-(p-styryl)-1,1-butanediphosphonate was used instead of tetraethyl 8-(p-styryl)-1,1-octanediphosphonate, to obtain poly(tetraethyl 4-(p-styryl)-1,1-butanediphosphonate).

[0426] Using deuterated chloroform, １ H-NMR measurement was carried out. １ The H-NMR spectrum is shown by the dashed line.

[0427] The peaks derived from the vinyl group protons disappeared, and broad signals derived from the protons c' to j' were observed at positions similar to the chemical shifts in the monomer, suggesting that a polymer was obtained.

[0428] GPC measurement of poly(tetraethyl 4-(p-styryl)-1,1-butanediphosphonate) was carried out in the same manner as in Example 1. FIG. 17 shows a GPC chromatogram of poly(tetraethyl 4-(p-styryl)-1,1-butanediphosphonate). When the molecular weight was calibrated using standard polystyrene, the Mw / Mn and Mn of poly(tetraethyl 4-(p-styryl)-1,1-butanediphosphonate) were 1.45 and 27 kJ, respectively.

[0429] (Third Step) sbdPA was synthesized by carrying out a deprotection reaction in the same manner as in the third step of Example 1, except that poly(tetraethyl 4-(p-styryl)-1,1-butanediphosphonate) was used instead of poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate).

[0430] sbdPA was dissolved in deuterated methanol. １ H-NMR measurement was performed. In FIG. 16, the solid line indicates the １ The H-NMR spectrum is shown.

[0431] The peak at about 4.1 ppm, which is attributable to the proton of the methylene group adjacent to the oxygen atom of the phosphonate diester unit, almost disappeared, confirming that deprotection had proceeded to 99%.

[0432] The sharp peak near 3.3 ppm is a peak derived from methanol, and the peak near 4.8 ppm is a peak derived from residual water in the polymer.

[0433] Example 4 In Example 4, hexaethyl 8-(p-styryl)-1,1-octanetriphosphonate was synthesized as a monomer having three phosphonate ester units per alkylene spacer via an alkylene spacer, using tetraethyl 8-(p-styryl)-1,1-octanediphosphonate synthesized in the first step of Example 1, according to Scheme 7 below (first step).

[0434]

[0435] Subsequently, this monomer was polymerized according to the following scheme 8 (second step).

[0436]

[0437] The alkyl protecting groups of the obtained poly(hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate) were deprotected to synthesize poly(8-(p-styryl)-1,1,1-octanetriphosphonic acid) (hereinafter also referred to as "sotPA"), which is a polymer having three phosphonic acid groups per spacer via an alkylene spacer (third step).

[0438] This sotPA was formed into a membrane to produce the proton-conductive electrolyte membrane of Example 4 (fourth step).

[0439] (Step 1) In a literature article (J. Org. Chem. 2011, 76, 8807-8813.), a compound having an alkylene triphosphonic acid hexaester structure is synthesized by reacting a compound having an alkylene diphosphonic acid tetraester structure with sodium bis(trimethylsilyl)amide, then reacting the resulting compound with chlorodiethyl phosphite, and then oxidizing the resulting compound with hydrogen peroxide. Based on this reaction, hexaethyl 8-(p-styryl)-1,1,1-octane triphosphonate was synthesized.

[0440] Specifically, 0.500 g (1.02 mmol) of tetraethyl 8-(p-styryl)-1,1-octanediphosphonate synthesized in the first step of Example 1 was dissolved in 6.5 mL of dehydrated THF under a nitrogen atmosphere and cooled to 0° C. To this was added 0.81 mL (1.54 mmol) of a THF solution of sodium bis(trimethylsilyl)amide (concentration: 1.9 mol / L), and the mixture was stirred for 30 minutes.

[0441] To this was added 0.40 mL (0.43 g, 2.8 mmol) of diethyl chlorophosphite, and the mixture was stirred for 30 minutes. 2.0 mL (2.3 g, 18 mmol) of aqueous hydrogen peroxide (concentration: 35%) was added, and the mixture was further stirred for 1.5 hours to synthesize hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate.

[0442] The volatile solvent (THF) was evaporated by rotary evaporation. After extraction by liquid separation, the solvent used in the liquid separation was removed by rotary evaporation. Furthermore, unreacted diethyl chlorophosphite and by-products were removed by vacuum distillation.

[0443] The resulting liquid was passed through a silica gel column for separation and purification to obtain hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate. Ethyl acetate, ethanol, and propanol were used as developing solvents.

[0444] The liquid obtained after purification was dissolved in deuterated chloroform. １ H-NMR measurement was carried out. １ The H-NMR spectrum is shown.

[0445] The chemical shifts of the vinyl group, benzene ring, and benzyl protons (a to f) remained almost unchanged, while the peak at 2.3 ppm derived from the methine group protons next to the two phosphorus atoms observed in tetraethyl 8-(p-styryl)-1,1-octanediphosphonate disappeared.

[0446] Furthermore, the integral ratio of the peak derived from the proton (f) of the methylene group adjacent to the benzyl position to the peak derived from the proton (m) of the methylene group adjacent to the oxygen atom of the phosphonate diester unit was approximately 2:6, confirming that hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate was obtained.

[0447] The peak at 7.27 ppm is due to chloroform, the peaks at 2.1 and 4.1 ppm are due to ethyl acetate, and the peaks at 0.9 and 3.6 ppm are due to 1-propanol.

[0448] (Second Step) Monomers were polymerized in the same manner as in the second step of Example 1, except that hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate was used instead of tetraethyl 8-(p-styryl)-1,1-octanediphosphonate, to obtain poly(hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate).

[0449] Using deuterated chloroform, １ H-NMR measurement was carried out. Figure 19 shows the structure of poly(8-(p-styryl)-1,1,1-octanetriphosphonic acid hexaethyl). １ The H-NMR spectrum is shown by the dashed line.

[0450] The peaks derived from the vinyl group protons disappeared, and broad signals derived from the c' to m' protons were observed at positions similar to the chemical shifts in the monomer, suggesting that a polymer was obtained.

[0451] GPC measurement of poly(hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate) was carried out in the same manner as in Example 1. FIG. 20 shows a GPC chromatogram of poly(hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate). When the molecular weight was calibrated using standard polystyrene, the Mw / Mn and Mn of poly(hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate) were found to be 1.78 and 28 kJ, respectively.

[0452] (Third Step) A deprotection reaction was carried out in the same manner as in the third step of Example 1, except that poly(hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate) was used instead of poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate), to synthesize sotPA.

[0453] sotPA was dissolved in deuterated methanol. １ H-NMR measurement was performed. In FIG. 19, the solid line indicates the １ The H-NMR spectrum is shown.

[0454] The peak at about 4.1 ppm, which is attributable to the proton of the methylene group adjacent to the oxygen atom of the phosphonate diester, almost disappeared, confirming that deprotection had proceeded to 99%.

[0455] The sharp peak near 3.3 ppm is a peak derived from methanol, and the peak near 4.8 ppm is a peak derived from residual water in the polymer.

[0456] Example 5 In Example 5, p-(9-(p-styryl)-nonyl)pyridine was synthesized as a monomer having a basic functional group using p-(8-bromooctyl)styrene synthesized in Step 1-1 of Example 1 via an alkylene spacer according to the following scheme 9 (first step).

[0457]

[0458] Subsequently, according to the following scheme 10, p-(9-(p-styryl)-nonyl)pyridine and tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate synthesized in the first step of Example 2 were copolymerized (second step).

[0459]

[0460] The alkyl protecting groups of the obtained poly((9-(p-styryl)-1,1-nonanediphosphonic acid tetraisopropyl)-co-(p-(9-(p-styryl)-nonyl)pyridine)) were deprotected to synthesize poly((9-(p-styryl)-1,1-nonanediphosphonic acid)-co-(p-(9-(p-styryl)-nonyl)pyridine)) (hereinafter also referred to as "sndPA-co-snPy") (third step).

[0461] (Step 1) In a literature article (Macromolecules 2010, 43, 1761-1770.), p-methylpyridine (also known as γ-picoline) was reacted with LDA, and then further reacted with p-bromomethylstyrene to synthesize p-(2-(p-styryl)-ethyl)pyridine (also known as (p-pyridylethyl)-p-vinylbenzene). Based on this reaction, 4-(9-(p-styryl)-nonyl)pyridine was synthesized.

[0462] Specifically, 0.931 g (10.0 mmol) of p-methylpyridine was dissolved in 5 mL of dehydrated THF and cooled to -80°C. 5.0 mL (10 mmol) of a THF / heptane / ethylbenzene solution of LDA (concentration: 2 mol / L) was added and stirred for 1 hour. 2.72 g (9.2 mmol) of p-(8-bromooctyl)styrene was added and stirred for 2 hours, and then stirred at room temperature overnight. Pure water was then added to terminate the reaction, synthesizing p-(9-(p-styryl)-nonyl)pyridine.

[0463] The volatile solvent was evaporated by rotary evaporation. After extraction by liquid separation, the solvent used in the liquid separation was removed by rotary evaporation. The resulting liquid was separated and purified by passing it through a silica gel column to obtain p-(9-(p-styryl)-nonyl)pyridine.

[0464] The developing solvents used were chloroform and methanol.

[0465] The liquid obtained after purification was dissolved in deuterated chloroform. １ H-NMR measurement was carried out. １ The H-NMR spectrum is shown.

[0466] Compared with the H-NMR spectrum of p-(8-bromooctyl)styrene shown in Figure 1, the chemical shifts of the protons (a-f) attached to the vinyl group, benzene ring, and benzyl position were almost unchanged. On the other hand, the peaks derived from the methylene group attached to the bromo group of p-(8-bromooctyl)styrene and the protons (m'', l'') of the adjacent methylene group disappeared.

[0467] Furthermore, a new peak derived from the proton (p) of the methine group adjacent to the nitrogen atom in the pyridyl group appeared at around 8.5 ppm, confirming that p-(9-(p-styryl)-nonyl)pyridine was obtained.

[0468] The peak at 3.5 ppm is due to methanol, and the peak at 7.27 ppm is due to chloroform.

[0469] The liquid obtained after purification was dissolved in deuterated chloroform. １３ C-NMR measurement was also carried out. １３ The C-NMR spectrum is shown.

[0470] The 4-(8-bromooctyl)styrene shown in FIG. １３ Comparing with the C-NMR spectrum, the chemical shifts of the vinyl group and benzene ring carbons (a to f) were almost unchanged. On the other hand, the peaks derived from the methylene group carbons g to o shifted in the range of 29 to 36 ppm, and new peaks (p, q, r) derived from the pyridyl group carbons appeared in the vicinity of 124 to 152 ppm, confirming that p-(9-(p-styryl)-nonyl)pyridine was obtained.

[0471] The peak near 77 ppm is a peak derived from chloroform.

[0472] (Second Step) 1.05 g (1.87 mmol) of p-(9-(p-styryl)-nonyl)pyridine and 0.106 g (0.344 mmol) of tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate obtained in the first step of Example 2 were weighed out, respectively, and 21.4 μL (0.38 μmol) of a diethylbenzene solution of DDAMT (concentration: 2.6 mg / mL) and 133 μL (1.1 μmol) of a diethylbenzene solution of AIBN (concentration: 2.9 mg / mL) were added thereto, and the mixture was mixed in a round-bottom flask equipped with a stopcock to prepare a solution.

[0473] A polymerization reaction was carried out at 120°C in the same manner as in the second step of Example 1, and purification was carried out by a reprecipitation method, thereby obtaining purified poly((tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate)-co-(p-(9-(p-styryl)-nonyl)pyridine)).

[0474] Using deuterated chloroform, １ 1H-NMR measurement was carried out. Fig. 23 shows the 1H-NMR spectrum of poly((tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate)-co-(p-(9-(p-styryl)-nonyl)pyridine)).

[0475] The peaks derived from the vinyl group protons disappeared, and broad signals derived from the co and c'-o' protons were observed at positions similar to the chemical shifts in the monomer, suggesting that a polymer was obtained.

[0476] In the same manner as in Example 1, GPC measurement of poly((tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate)-co-(p-(9-(p-styryl)-nonyl)pyridine)) was carried out.

[0477] FIG. 24 shows a GPC chromatogram of poly((tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate)-co-(p-(9-(p-styryl)-nonyl)pyridine)). When the molecular weight was calibrated using standard polystyrene, the Mw / Mn and Mn of poly(tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate)-co-(p-(9-(p-styryl)-nonyl)pyridine)) were 1.56 and 42 kJ, respectively.

[0478] (Third Step) sndPA-co-snPy was synthesized by carrying out a deprotection reaction in the same manner as in the third step of Example 1, except that poly((9-(p-styryl)-1,1-nonanediphosphonate tetraisopropyl)-co-(p-(9-(p-styryl)-nonyl)pyridine)) was used instead of poly(8-(p-styryl)-1,1-octanediphosphonate tetraethyl).

[0479] Example 6 In Example 6, 1-ethyl-4-(9-(p-styryl)-nonyl)pyridinium bromide was synthesized according to Scheme 11 below, using p-(9-(p-styryl)-nonyl)pyridine synthesized in the first step of Example 5.

[0480]

[0481] 0.050 g (0.16 mmol) of p-(9-(p-styryl)-nonyl)pyridine and 0.15 g (1.3 mmol) of bromoethane were added and stirred at room temperature for 48 hours. After that, the mixture was dried in a vacuum to synthesize 1-ethyl-4-(9-(p-styryl)-nonyl)pyridinium bromide.

[0482] The resulting liquid was dissolved in deuterated chloroform. １ H-NMR measurement was carried out. １ The H-NMR spectrum is shown.

[0483] p-(9-(p-styryl)-nonyl)pyridine shown in FIG. １Compared with the H-NMR spectrum, the chemical shifts of the protons (a to m) attached to the vinyl group, benzene ring, and alkylene group except for the one adjacent to the pyridinium group were almost unchanged.

[0484] On the other hand, the methylene group (n) next to the pyridinium group and the protons (o and p) of the pyridinium group appeared at 2.9, 7.8, and 9.3 ppm, respectively, shifted downfield. Furthermore, new peaks attributable to the protons (q and r) of the ethyl group appeared near 5.0 and 1.7 ppm, confirming that 1-ethyl-4-(9-(p-styryl)-nonyl)pyridinium bromide was obtained.

[0485] The peak at 7.27 ppm is a peak derived from chloroform.

[0486] Example 7 In Example 7, poly(p-n-octylstyrene)-b-poly(diethyl 8-(p-styryl)-1-octanephosphonate) (also referred to as poly(1-(p-styryl)-n-octane)-b-poly(diethyl 8-(p-styryl)-1-octanephosphonate); hereinafter, also referred to as "so-soPdE") was synthesized as a block copolymer using the diethyl 8-(p-styryl)-1-octanephosphonate obtained in Step 1-2 of Example 1, according to Scheme 12 below (first step).

[0487]

[0488] Next, the protecting groups of the poly(diethyl 8-(p-styryl)-1-octanephosphonate) block were deprotected to synthesize poly(p-n-octylstyrene)-b-poly(8-(p-styryl)-1-octanephosphonic acid) (also called poly(1-(p-styryl)-n-octane)-b-poly(8-(p-styryl)-1-octanephosphonic acid); hereinafter, also referred to as "so-soPA") having a proton-donating group (second step).

[0489] This so-soPA was processed into a membrane to produce the proton conductive membrane of Example 7 (hereinafter also referred to as "so-soPA-1 membrane") (third step).

[0490] In the term "so-soPA," "so" is an abbreviation for poly(p-n-octylstyrene) (also called poly(1-(p-styryl)-n-octane)), and "so" is a hydrophobic hydrocarbon-based vinyl polymer having a glass transition temperature (Tg) of 30°C or lower, i.e., the "b block" as defined in the present invention.

[0491] In addition, in the term "so-soPA," "soPA" is an abbreviation for poly(8-(p-styryl)-1-octanephosphonic acid), which is a polymer having a proton-donating group, i.e., the "a block" referred to in the present disclosure.

[0492] (1-1) First Step (Step 1-1) Monomers were polymerized in the same manner as in the second step of Example 1, except that commercially available p-n-octylstyrene was used instead of tetraethyl 8-(p-styryl)-1,1-octanediphosphonate, to synthesize poly(p-n-octylstyrene) (also referred to as poly(1-(p-styryl)-n-octane), hereinafter also referred to as “so”).

[0493] Using deuterated chloroform, １ When H-NMR measurement was carried out, the number average degree of polymerization was estimated to be 90 and Mn was estimated to be 19k. １ The H-NMR spectrum is shown.

[0494] GPC measurement of so was carried out in the same manner as in Example 1. The GPC chromatogram of so is shown by the dashed line in Figure 27. When the molecular weight was calibrated using standard polystyrene, the Mw / Mn of so was found to be 1.21.

[0495] (Step 1-2) The so obtained in Step 1-1 had a RAFT agent residue introduced at the molecular chain terminal. Diethyl 8-(p-styryl)-1-octanephosphonate monomer was polymerized in the same manner as in Step 1 of Example 1, except that this os was used as a macro RAFT agent (referred to as a "macro RAFT agent" because it is a RAFT agent with a large molecular weight), thereby obtaining an so-soPdE diblock copolymer.

[0496] so-soPdE was dissolved in deuterated chloroform. １The number-average degree of polymerization was determined by H-NMR measurement. １ The H-NMR spectrum shows that the number average degree of polymerization of the so block was 130, the number average degree of polymerization of the soPdE block was 1410, and the overall Mn was 516kJ.

[0497] GPC measurement of so-soPdE was carried out in the same manner as in Example 1. The GPC chromatogram of so-soPdE is shown by the solid line in Figure 27. The peak of so-soPdE was shifted to the lower elution time side compared to the peak of so, confirming the formation of a block copolymer. The Mw / Mn of so-soPdE was 2.29.

[0498] (1-2) Second Step: The deprotection reaction of so-soPdE was carried out in the same manner as in the third step of Example 1 to obtain a so-soPA diblock copolymer.

[0499] so-soPA was dissolved in a mixed solvent of deuterated chloroform and deuterated methanol, １ H-NMR measurement was performed. In FIG. 26, the solid line shows the １ The H-NMR spectrum shows that the signal at about δ=4.0, which is assigned to the ester of the soPdE block, disappeared, confirming that the deprotection reaction had progressed to 99% or more.

[0500] The peaks around 3.4 and 7.2 ppm are due to methanol and chloroform, and the peak around 4.9 ppm is due to residual water in the polymer.

[0501] (1-3) Third Step: A so-soPA-1 membrane was prepared in the same manner as in the fourth step of Example 1, except that a mixed solvent of 1-propanol and acidic water (pH 1 or less) was used as the solvent.

[0502] Example 8 In Example 8, poly(p-n-octylstyrene)-b-poly(diethyl 4-(p-styryl)-1-butanephosphonate) (also referred to as poly(1-(p-styryl)-n-octane)-b-poly(diethyl 4-(p-styryl)-1-butanephosphonate), hereinafter also referred to as "so-sbPdE") was prepared as a block copolymer in the same manner as in Example 7, except that diethyl 4-(p-styryl)-1-butanephosphonate obtained in step 1-2 of Example 3 was used instead of diethyl 8-(p-styryl)-1-octanephosphonate.

[0503] The number-average degree of polymerization of the so block was 620, the number-average degree of polymerization of the sbPdE block was 2075, the overall Mn was 749k, and Mw / Mn was 4.72.) was synthesized, and the protecting groups of the poly(4-(p-styryl)-1-butanephosphonic acid diethyl) block were deprotected to obtain poly(p-n-octylstyrene)-b-poly(4-(p-styryl)-1-butanephosphonic acid) (also referred to as poly(1-(p-styryl)-n-octane)-b-poly(4-(p-styryl)-1-butanephosphonic acid); hereinafter, also referred to as "so-sbPA"). This so-sbPA was formed into a membrane to produce the proton-conductive membrane of Example 8 (hereinafter, also referred to as "so-sbPA-1 membrane"). Scheme 13 shows the synthesis scheme of the polymer.

[0504]

[0505] The proton conductivity of the proton-conducting electrolyte membrane of Example 8 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Example 8 are summarized in Table 1. The membrane of Example 8 exhibited proton conductivities of, for example, 14 mS / cm at 100°C and 80% RH, 6.2 mS / cm at 100°C and 60% RH, 2.6 mS / cm at 100°C and 40% RH, and 1.2 mS / cm at 100°C and 20% RH, which were higher than the proton-conducting electrolyte membranes of Comparative Examples 1 and 2.

[0506] Example 9 In Example 9, diethyl 4-(p-styryl)-1-butanephosphonate obtained in step 1-2 of Example 3 was used, and monomer polymerization and a deprotection reaction were carried out in the same manner as in step 2 and step 3 of Example 3, to synthesize poly(4-(p-styryl)-1-butanephosphonic acid) (hereinafter, also referred to as "sbPA"), which is a polymer having one phosphonic acid group per spacer via an alkylene spacer.

[0507] A protonic polymer electrolyte membrane (hereinafter also referred to as "sbPA / PPS membrane") was fabricated by combining this with sbPA and a commercially available nonwoven fabric made of polyphenylene sulfide (manufactured by Hirose Paper Co., Ltd., hereinafter also referred to as "PPS nonwoven fabric").

[0508] Furthermore, when the molecular weight was calibrated by GPC measurement using standard polystyrene, the Mw / Mn and Mn of the polymer before the deprotection reaction were 1.82 and 130 kJ, respectively.

[0509] The sbPA and the PPS nonwoven fabric were composited as follows.

[0510] First, sbPA was dissolved in a mixed solvent of methanol and alkaline water (pH 13), and the resulting solution was impregnated into a 4 cm square PPS nonwoven fabric. The fabric was then left to stand at 60°C to evaporate the solvent. This procedure was repeated multiple times, and the resulting membrane was then heat-pressed at 120°C for 1 minute. The resulting membrane was then immersed in acidic water (pH 1) for 1 hour, and thoroughly dried to prepare the proton-conducting electrolyte membrane of Example 9.

[0511] The proton conductivity of the proton-conducting electrolyte membrane of Example 7 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Example 9 are summarized in Table 1. The membrane of Example 9 exhibited a proton conductivity of 1.2 mS / cm at 120°C and 40% RH and 0.46 mS / cm at 120°C and 20% RH.

[0512] To evaluate the mechanical properties of the membrane of Example 9, a tensile test was carried out.

[0513] Specifically, the sbPA / PPS membrane was punched with a punching die corresponding to the dumbbell No. 7 shape described in Japanese Industrial Standard JIS K6251:2017 (corresponding to Type 4 in International Organization for Standardization ISO37:2017) to prepare a test specimen. The thickness of the test specimen was approximately 0.12 mm.

[0514] The measuring device used was an AGS-X manufactured by Shimadzu Corporation, a 50N load cell, and a pneumatic flat gripper. The tensile test was carried out at an air pressure of 0.40 MPa, room temperature, a distance between the grippers of approximately 10 mm, and an initial strain rate of 0.10 / s (tensile rate of approximately 1.0 mm / s).

[0515] The stress-strain curve, which is the result of the tensile test, is shown by the solid line in Figure 28. The mechanical strength and breaking elongation were 11.9 MPa and 24%, respectively, indicating good mechanical properties.

[0516] Comparative Example 3 In Comparative Example 3, the sbPA obtained in Example 9 was processed into a membrane in the same manner as in the fourth step of Example 1, to produce a proton-conductive electrolyte membrane of Comparative Example 3.

[0517] The conductivity of the proton-conducting electrolyte membrane of Comparative Example 3 is summarized in Table 1. The membrane of Comparative Example 3 exhibited, for example, a proton conductivity of 2.6 mS / cm at 120°C and 40% RH, and 1.1 mS / cm at 120°C and 20% RH.

[0518] A tensile test was attempted on the membrane of Comparative Example 3 in the same manner as the membrane of Example 9, but the membrane was so brittle that it could not be punched out with a punching blade corresponding to a No. 7 dumbbell shape.

[0519] These results demonstrate that the membrane of Example 9 has superior mechanical strength compared to the membrane of Comparative Example 3. It is believed that the membrane of Example 9 has a higher mechanical strength as a whole than sbPA alone because sbPA is combined with the PSS nonwoven fabric, which has high mechanical strength.

[0520] Example 10 In Example 10, a protonic polymer electrolyte membrane (hereinafter also referred to as "so-soPA / PPS membrane") was prepared by combining so-soPA and a PPS nonwoven fabric in the same manner as in Example 9, except that so-soPA obtained in the second step of Example 7 was used instead of sbPA and a mixed solvent of 1-propanol and acidic water (pH 1 or less) was used as the solvent.

[0521] The proton conductivity of the proton-conducting electrolyte membrane of Example 10 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Example 10 are summarized in Table 1. The membrane of Example 10 exhibited, for example, a proton conductivity of 1.9 mS / cm at 120°C and 40% RH and 1.1 mS / cm at 120°C and 20% RH.

[0522] Example 11 In Example 11, poly(p-n-octylstyrene)-b-poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate) (also referred to as poly(1-(p-styryl)-n-octane)-b-poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate), hereinafter also referred to as "so-sodPAtE"), was prepared as a block copolymer in the same manner as in Example 7, except that tetraethyl 8-(p-styryl)-1,1-octanediphosphonate obtained in step 1-3 of Example 1 was used instead of diethyl 8-(p-styryl)-1-octanephosphonate.

[0523] The number-average degree of polymerization of the so block was 130, the number-average degree of polymerization of the soPdE block was 3120, and the overall Mn was 1552k, with Mw / Mn = 3.5. The protecting groups of the poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate) block were deprotected to obtain poly(p-n-octylstyrene)-b-poly(8-(p-styryl)-1,1-octanediphosphonic acid) (also referred to as poly(1-(p-styryl)-n-octane)-b-poly(8-(p-styryl)-1,1-octanediphosphonic acid); hereinafter, also referred to as "so-sodPA"). This so-sodPA was formed into a membrane, thereby producing the proton-conductive membrane of Example 13 (hereinafter, also referred to as "so-sodPA membrane"). Scheme 14 shows the synthesis scheme of the polymer.

[0524]

[0525] The proton conductivity of the proton-conducting electrolyte membrane of Example 11 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Example 11 are summarized in Table 1. The membrane of Example 13 exhibited, for example, proton conductivities of 140 mS / cm at 100°C and 80% RH, 63 mS / cm at 100°C and 60% RH, 27 mS / cm at 100°C and 40% RH, and 9.1 mS / cm at 100°C and 20% RH, which were higher than the proton-conducting electrolyte membranes of Comparative Examples 1 and 2.

[0526] Example 12 In Example 12, so-sbPdE (number-average degree of polymerization of so blocks: 322, number-average degree of polymerization of sbPdE blocks: 1825, overall Mn: 611k, Mw / Mn = 2.40) was synthesized in the same manner as in Example 8, except that the amounts of p-n-octylstyrene monomer and 4-(p-styryl)-1-butanephosphonic acid diethyl were appropriately changed. The protecting groups of the poly(4-(p-styryl)-1-butanephosphonic acid diethyl) blocks were deprotected to obtain so-sbPA, and this so-sbPA was formed into a membrane, thereby producing a proton conductive membrane of Example 12 (hereinafter also referred to as "so-sbPA-2 membrane").

[0527] The proton conductivity of the proton-conducting electrolyte membrane of Example 12 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Example 12 are summarized in Table 1. The membrane of Example 12 exhibited, for example, a proton conductivity of 10 mS / cm at 100°C and 80% RH, 3.8 mS / cm at 100°C and 60% RH, 1.7 mS / cm at 100°C and 40% RH, and 0.64 mS / cm at 100°C and 20% RH.

[0528] Example 13 In Example 13, so-sbPdE (number-average degree of polymerization of so blocks: 322, number-average degree of polymerization of sbPdE blocks: 3703, overall Mn: 1170k, Mw / Mn = 5.13) was synthesized in the same manner as in Example 8, except that the amounts of p-n-octylstyrene monomer and 4-(p-styryl)-1-butanephosphonic acid diethyl were appropriately changed. The protecting groups of the poly(4-(p-styryl)-1-butanephosphonic acid diethyl) blocks were deprotected to obtain so-sbPA, and this so-sbPA was formed into a membrane to produce a proton conductive membrane of Example 13 (hereinafter also referred to as "so-sbPA-3 membrane").

[0529] The proton conductivity of the proton-conducting electrolyte membrane of Example 13 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Example 13 are summarized in Table 1. The membrane of Example 13 exhibited, for example, a proton conductivity of 11 mS / cm at 100°C and 80% RH, 6.3 mS / cm at 100°C and 60% RH, 3.0 mS / cm at 100°C and 40% RH, and 1.6 mS / cm at 100°C and 20% RH.

[0530] Example 14 In Example 14, so-sbPdE (number-average degree of polymerization of so blocks: 322, number-average degree of polymerization of sbPdE blocks: 349, overall Mn: 173k, Mw / Mn = 3.55) was synthesized in the same manner as in Example 8, except that the amounts of p-n-octylstyrene monomer and 4-(p-styryl)-1-butanephosphonic acid diethyl were appropriately changed. The protecting groups of the poly(4-(p-styryl)-1-butanephosphonic acid diethyl) blocks were deprotected to form so-sbPA, and this so-sbPA was formed into a membrane, thereby producing a proton conductive membrane of Example 14 (hereinafter also referred to as "so-sbPA-4 membrane").

[0531] The proton conductivity of the proton-conducting electrolyte membrane of Example 14 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Example 14 are summarized in Table 1. The membrane of Example 14 exhibited, for example, a proton conductivity of 6.3 mS / cm at 100°C and 80% RH, 2.1 mS / cm at 100°C and 60% RH, 0.69 mS / cm at 100°C and 40% RH, and 0.18 mS / cm at 100°C and 20% RH.

[0532] Example 15 In Example 15, so-soPdE (number-average degree of polymerization of so blocks: 45, number-average degree of polymerization of soPdE blocks: 255, overall Mn: 100k, Mw / Mn = 1.52) was synthesized in the same manner as in Example 7, except that the amounts of p-n-octylstyrene monomer and 8-(p-styryl)-1-octanephosphonic acid diethyl were appropriately changed. The protecting groups of the poly(8-(p-styryl)-1-octanephosphonic acid diethyl) blocks were deprotected to obtain so-soPA, which was then formed into a membrane, thereby producing a proton conductive membrane of Example 15 (hereinafter also referred to as "so-soPA-2 membrane").

[0533] The proton conductivity of the proton-conducting electrolyte membrane of Example 15 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Example 15 are summarized in Table 2. The membrane of Example 15 exhibited, for example, a proton conductivity of 7.9 mS / cm at 120°C and 40% RH and 5.0 mS / cm at 120°C and 20% RH.

[0534] A tensile test was performed on the membrane of Example 15 in the same manner as the membrane of Example 9, except that the test specimen was a 5 mm x 20 mm strip, the distance between the grippers was approximately 5 mm, and the initial strain rate was 0.005 / s (tensile rate approximately 0.025 mm / s). Figure 29 shows the stress-strain curve obtained as a result of the tensile test, as a broken line. The Young's modulus (the slope of the stress-strain curve at strains of 0 to 1%), mechanical strength, elongation at break, and toughness (the value of the internal area of ​​the stress-strain curve) were 77 MPa, 3.2 MPa, 6.0%, and 120 kJ / m, respectively. ３ It was.

[0535] <Comparative Example 4> In Comparative Example 4, soPdE (Mn: 55k, Mw / Mn = 1.96) was synthesized in the same manner as in Comparative Example 1, except that the amount of diethyl 8-(p-styryl)-1-octanephosphonate was appropriately changed. The protecting groups of the poly(diethyl 8-(p-styryl)-1-octanephosphonate) block were deprotected to obtain soPA, and this soPA was made into a membrane to produce the proton conductive membrane of Comparative Example 4 (hereinafter also referred to as "soPA-2 membrane").

[0536] The proton conductivity of the proton-conducting electrolyte membrane of Comparative Example 4 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Comparative Example 4 are summarized in Table 2. The membrane of Comparative Example 4 exhibited, for example, a proton conductivity of 7.5 mS / cm at 120°C and 40% RH and 4.4 mS / cm at 120°C and 20% RH. Therefore, although the membrane of Example 15 contained so blocks and therefore had a lower acid group density than the membrane of Comparative Example 4, it maintained a conductivity equivalent to that of the membrane of Comparative Example 4.

[0537] In the soPA-2 membrane of Comparative Example 4, phase separation occurs during membrane formation into a phase consisting of hydrophilic phosphonic acid groups and a phase consisting of hydrophobic alkylene spacer groups and polystyrene main chains, and it is thought that each phase tends to be oriented parallel to the membrane surface.

[0538] On the other hand, in the so-soPA-2 membrane of Example 11, in addition to the phase separation within the soPA block, phase separation also occurred between the so and soPA blocks. As a result, it is thought that the conductive phosphonic acid group phase was likely to be oriented perpendicular to the membrane surface. This change in orientation facilitated the efficient formation of a network of the phosphonic acid group phase, which is thought to have resulted in conductivity equivalent to that of the membrane of Comparative Example 4.

[0539] A tensile test was carried out on the membrane of Comparative Example 4 in the same manner as the membrane of Example 15. The stress-strain curve showing the results of the tensile test is shown by the dotted line in Figure 29. The Young's modulus, mechanical strength, elongation at break, and toughness were 120 MPa, 2.7 MPa, 2.5%, and 44 kJ / m, respectively. ３ The film of Example 15 exhibited better breaking elongation and toughness than the film of Comparative Example 4.

[0540] The membrane of Example 15 stretched more than the membrane of Comparative Example 4. This is thought to be because the stress generated during stretching was dispersed in the flexible domains formed by the so blocks. As a result, premature breakage of the membrane was suppressed, and the membrane of Example 15 exhibited higher toughness than the membrane of Comparative Example 4.

[0541] Example 16 In Example 16, so-soPdE (number-average degree of polymerization of so blocks: 105, number-average degree of polymerization of soPdE blocks: 234, overall Mn: 105k, Mw / Mn = 1.63) was synthesized in the same manner as in Example 7, except that the amounts of p-n-octylstyrene monomer and 8-(p-styryl)-1-octanephosphonic acid diethyl were appropriately changed. The protecting groups of the poly(8-(p-styryl)-1-octanephosphonic acid diethyl) blocks were deprotected to obtain so-soPA, which was then formed into a membrane, thereby producing a proton conductive membrane of Example 16 (hereinafter also referred to as "so-soPA-3 membrane").

[0542] The proton conductivity of the proton-conducting electrolyte membrane of Example 16 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Example 16 are summarized in Table 2. The membrane of Example 16 exhibited, for example, a proton conductivity of 5.4 mS / cm at 120°C and 40% RH and 3.3 mS / cm at 120°C and 20% RH, which was on the same order of conductivity as the membrane of Comparative Example 4.

[0543] A tensile test was carried out on the membrane of Example 16 in the same manner as the membrane of Example 15. The stress-strain curve showing the results of the tensile test is shown by the dashed line in Figure 29. The Young's modulus, mechanical strength, elongation at break, and toughness were 83 MPa, 3.4 MPa, 5.5%, and 120 kJ / m, respectively. ３ The film of Example 12 exhibited better breaking elongation and toughness than the film of Comparative Example 4.

[0544] The membrane of Example 16 stretched more than the membrane of Comparative Example 4. This is thought to be because the stress generated during stretching was dispersed in the flexible domains formed by the so blocks. As a result, premature breakage of the membrane was suppressed, and the membrane of Example 16 exhibited higher toughness than the membrane of Comparative Example 4.

[0545] Example 17 In Example 17, so-soPdE (number-average degree of polymerization of so blocks: 130, number-average degree of polymerization of soPdE blocks: 231, overall Mn: 110k, Mw / Mn = 1.69) was synthesized in the same manner as in Example 7, except that the amounts of p-n-octylstyrene monomer and 8-(p-styryl)-1-octanephosphonic acid diethyl were appropriately changed. The protecting groups of the poly(8-(p-styryl)-1-octanephosphonic acid diethyl) blocks were deprotected to obtain so-soPA, which was then formed into a membrane to produce the proton conductive membrane of Example 17 (hereinafter also referred to as "so-soPA-4 membrane").

[0546] The proton conductivity of the proton-conducting electrolyte membrane of Example 17 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Example 17 are summarized in Table 2. The membrane of Example 17 exhibited, for example, a proton conductivity of 3.7 mS / cm at 120°C and 40% RH and 2.7 mS / cm at 120°C and 20% RH, which was on the same order of conductivity as the membrane of Comparative Example 4.

[0547] A tensile test was carried out on the membrane of Example 17 in the same manner as the membrane of Example 15. The stress-strain curves resulting from the tensile test are shown by solid lines in Figure 29. The Young's modulus, mechanical strength, elongation at break, and toughness were 51 MPa, 3.5 MPa, 15%, and 360 kJ / m, respectively. ３ The film of Example 13 exhibited better breaking elongation and toughness than the film of Comparative Example 4.

[0548] The membrane of Example 17 stretched more than the membrane of Comparative Example 4 because the stress generated during stretching was dispersed in the flexible domains formed by the so blocks. As a result, premature breakage of the membrane was suppressed, and the membrane of Example 17 exhibited higher toughness than the membrane of Comparative Example 4.

[0549]

[0550]

[0551] Example 18 In Example 18, 7,7′-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate) was synthesized as a monomer having two phosphonate esters per alkylene spacer in accordance with Scheme 15 below (first step).

[0552]

[0553] Subsequently, this monomer is polymerized (second step) according to the following scheme 16, and the alkyl protecting groups of the resulting poly(7,7′-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate)) are deprotected to obtain poly(7,7′-(9H-fluorene-9,9-diyl)bis(1,1-heptanediphosphonic acid)), a polymer having two phosphonic acid groups per spacer via an alkylene spacer (hereinafter referred to as “fb(h)”). ｐ dPA) was synthesized (third step).

[0554]

[0555] This fb (h ｐ dPA) was formed into a membrane to prepare the proton-conducting electrolyte membrane of Example 1 (fourth step).

[0556] (Step 1) In a literature article (J. Org. Chem. 2011, 76, 8807-8813.), a compound having a bromoalkyl structure is reacted with sodium hydride, and then further reacted with methylene diphosphonic acid tetraester to synthesize a compound having an alkylene diphosphonic acid tetraester structure. Based on this reaction, 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate) was synthesized.

[0557] Specifically, 0.273 g (6.83 mmol) of sodium hydride (concentration 60 wt%) dispersed in liquid paraffin was dissolved in 2 mL of dehydrated THF under a nitrogen atmosphere, and 2.22 g (6.45 mmol) of tetraisopropyl methylenediphosphonate was added. Then, 0.998 g (1.53 mmol) of 2,7-dibromo-9,9-bis(6-bromohexyl)fluorene was added, followed by heating and stirring. The reaction was then quenched by adding a saturated aqueous solution of ammonium chloride.

[0558] Extraction was performed by a separation operation, and the solvent used in the separation operation was removed using rotary evaporation. Further separation and purification were carried out by passing through a silica gel column to obtain 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate). Ethyl acetate and 2-propanol were used as developing solvents.

[0559] The liquid obtained after purification was dissolved in deuterated chloroform. １ 30 shows the solid line (Example 18) of 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate). １ The H-NMR spectrum is shown.

[0560] In addition, in FIG. 30, the broken line (Example 19) shows the fluorene of 2,7-dibromo-9,9-bis(6-bromohexyl)fluorene. １ The H-NMR spectrum is shown.

[0561] The precursor, 2,7-dibromo-9,9-bis(6-bromohexyl)fluorene １ In the H-NMR spectrum, the proton (i′) of the methylene group to which the bromo group was attached was observed at around 3.3 ppm.

[0562] After the reaction １In the H-NMR spectrum, the peak derived from the proton (i') of the methylene group to which the bromo group is attached disappears, and a peak derived from the proton (k) of the methine group adjacent to the oxygen atom of the four phosphonate diester units appears at around 4.7 ppm, a peak derived from the proton (l) of the methyl group adjacent to that appears at around 1.3 ppm, and a peak derived from the methine group proton (j) adjacent to the two phosphorus atoms appears at 2.1 ppm. This suggests that 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate) was obtained.

[0563] The peak at 7.27 ppm is due to chloroform, and the peaks at 1.2 and 4.0 ppm are due to 2-propanol.

[0564] (Second Step) In a literature study (J. Am. Chem. Soc. 2007, 129, 11910-11911), 2,7-dibromo-9,9-dioctyl-9H-fluorene was polymerized using a nickel compound. Based on this reaction, poly(7,7'-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate)) was synthesized.

[0565] 0.705 g (2.56 mmol) of bis(1,5-cyclooctadiene)nickel(0), 0.297 g (1.90 mmol) of 2,2'-bipyridyl, and 0.220 g (2.03 mmol) of 1,5-cyclooctadiene were weighed out and added to 4.25 mL of N,N-dimethylformamide (DMF) with heating and stirring. 0.511 g (0.434 mmol) of 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate) obtained in the first step and 5.0 mL of toluene were added, and the mixture was stirred for an additional 4 days.

[0566] The resulting solution was washed with chloroform, hydrochloric acid, pure water, and saturated saline, and then reprecipitated with n-hexane to obtain purified poly(7,7'-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate)) (0.288 g).

[0567] Using deuterated chloroform, １ 31 shows the dotted line of poly(7,7'-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate)). １ The H-NMR spectrum is shown.

[0568] A broad signal was observed at a position almost identical to the chemical shift of the monomer, suggesting that a polymer was obtained.

[0569] Poly(7,7'-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate)) was dissolved in THF to prepare an approximately 0.1% by mass solution, and the molecular weight distribution (Mw / Mn) and number average molecular weight (Mn) were determined by gel permeation chromatography (GPC). Figure 32 shows the GPC chromatogram of poly(7,7'-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate)). The Mw / Mn and Mn, determined by molecular weight calibration using standard polystyrene, were 1.82 and 38 kJ, respectively.

[0570] The eluent used was a solvent mainly composed of THF, the flow rate was 1 mL / min, the temperature was 40°C, and the measurement was carried out using two connected TSKgel columns GMHHR-M manufactured by Tosoh Corporation.

[0571] (Third Step) In a literature article (Macromolecules, 2018, 51, 1120-1128.), poly(diethyl 4-styrenephosphonate) is reacted with bromotrimethylsilane, and then reacted with a methanol solvent and dialyzed to deprotect the alkyl groups of poly(diethyl 4-styrenephosphonate), thereby synthesizing poly(4-styrenephosphonic acid) having no alkylene spacer.

[0572] Using this reaction as a reference, poly(7,7'-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate)) obtained in the second step was reacted with bromotrimethylsilane, then with methanol, and dialyzed against water to carry out a deprotection reaction.

[0573] Specifically, 2.88 g (0.275 mmol in monomer units) of poly(7,7'-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate)) was dissolved in 5.0 mL of chloroform, 1.7 g (11 mmol) of bromotrimethylsilane was added, and the mixture was placed in a 40°C oil bath and stirred overnight. The polymer was reacted and dissolved in an excess amount of methanol, and then purified by dialysis using a cellulose dialysis tube and pure water. Finally, the water was evaporated to obtain fb(h ｐ dPA) was obtained.

[0574] fb (h ｐ dPA) in a mixed solvent of deuterated methanol and hydrochloric acid, １ H-NMR measurement was performed. ｐ dPA) １ The H-NMR spectrum is shown.

[0575] The peak at about 4.8 ppm derived from the proton (k') of the methine group adjacent to the oxygen atom of the phosphonate diester almost disappeared, confirming that deprotection had proceeded to 99%.

[0576] The peak near 3.3 ppm is a peak derived from methanol, and the peak near 5.7 ppm is a peak derived from hydrochloric acid.

[0577] (Fourth step) 30 mg of fb(h ｐ dPA) was dissolved in approximately 1.1 g of a mixed solvent of methanol and acidic water (pH 1 or less). The resulting solution was transferred to a polypropylene container and allowed to stand overnight at 60°C to evaporate the solvent, preparing a cast membrane. The membrane was then immersed in pure water at 60°C for 1 hour to prepare the proton-conducting electrolyte membrane of Example 11.

[0578] <Evaluation> (AC Impedance Measurement) Using a platinum mesh having a thickness of about 0.1 mm as an electrode, AC impedance measurement was carried out on the sample of the proton-conductive electrolyte membrane of Example 1.

[0579] A sample of the proton-conductive electrolyte membrane of Example 1 cut into a strip (thickness: 0.035 mm, width: 5.0 mm, length: 10 mm) was sandwiched between a pair of electrodes arranged opposite each other with an inter-electrode distance of 0.70 cm and an electrode width of 0.18 cm to prepare a measurement cell.

[0580] The measurement cell was placed in a small environmental test chamber (SH-242, manufactured by Espec Corporation), and the conditions were set at a temperature of 100°C and a relative humidity of 80% RH (partial pressure of water vapor pH2O = 818 hPa). Using a potentio / galvanostat VSP-300 (manufactured by BioLogic Science Instruments), the voltage was set to 50 mV and the frequency was set to 7 × 10 ６ The AC impedance was measured by changing the frequency in the range of 1 Hz to 1 Hz. The resistance value at the minimum point of the Nyquist plot was read as 2.7 × 10 ４ It was Omega.

[0581] The proton conductivity of this proton-conductive electrolyte membrane sample was calculated using the following formula (1) and was found to be 42 mS / cm (Table 2).

[0582] Proton conductivity = distance between electrodes / (membrane thickness x electrode width x resistance at the minimum point of the Nyquist plot) (1)

[0583] The relative humidity is 60% RH (p Ｈ２Ｏ = 613 hPa), 40% RH (p Ｈ２Ｏ =408hPa), 20%RH (p Ｈ２Ｏ = 204 hPa), and AC impedance measurements were performed. The relative humidity dependence of conductivity at 120 ° C was also measured in the same manner. The membrane of Example 18 exhibited a proton conductivity of 7.3 mS / cm at 120 ° C, 40% RH, and 1.8 mS / cm at 120 ° C, 20% RH, for example. The conductivity measurement results are summarized in Table 3, and the conductivities at 100 ° C and 120 ° C are represented by black circles (●) in Figure 33 (100 ° C) and Figure 34 (120 ° C), respectively.

[0584] (Water Resistance Evaluation) When the proton-conductive electrolyte membrane of Example 18 was immersed in water at 60°C for 2 hours, there was almost no change in the appearance of the membrane before and after immersion in water, and there was almost no evidence of the polymer dissolving into liquid water.

[0585] Furthermore, fb(h ｐ Poly(6,6'-(9H-fluorene-9,9-diyl)bis(1-hexanephosphonic acid diethyl)) ("fb(hPA)") was used as a comparative sample for the fb(hPA) membrane. ｘ The researchers at the University of Tokyo (also referred to as "Diethyl 1-hexanephosphonate") synthesized 6,6'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(diethyl 1-hexanephosphonate) as a monomer having one phosphonate ester per spacer via an alkylene spacer according to Scheme 17 below (FIG. 35).

[0586]

[0587] Subsequently, this monomer is polymerized in the same manner as in the second step of Example 18 according to the following scheme 18, and the alkyl protecting groups of the resulting poly(6,6'-(9H-fluorene-9,9-diyl)bis(diethyl 1-hexanephosphonate)) are deprotected in the same manner as in the third step of Example 1, thereby completing the synthesis.

[0588] Example 19 In Example 19, 7,7′-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate) was used, which was synthesized in the same manner as in the first step of Example 18, to synthesize 7,7′-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl heptane-1,1-diphosphonate-1-diethyl phosphonate) as a monomer having three phosphonate esters per spacer via alkylene spacers, according to Scheme 19 below.

[0589]

[0590] This monomer serves as a raw material for a polymer having three phosphonic acid groups per spacer via an alkylene spacer.

[0591] In a literature study (J. Org. Chem. 2011, 76, 8807-8813), a compound having an alkylene triphosphonic acid hexaester structure is synthesized by reacting a compound having an alkylene diphosphonic acid tetraester structure with sodium bis(trimethylsilyl)amide, followed by reaction with chlorodiethyl phosphite, and then oxidizing with hydrogen peroxide. Based on this reaction, 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(heptane-1,1-diphosphonic acid tetraisopropyl-1-diethyl phosphonate) was synthesized.

[0592] Specifically, 0.91 g (0.77 mmol) of 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate) synthesized in the same manner as in the first step of Example 18 was dissolved in dehydrated THF under an argon gas atmosphere and cooled to 0° C. 2.0 mL (3.8 mmol) of a THF solution of sodium bis(trimethylsilyl)amide (concentration: 1.9 mol / L) was added.

[0593] 0.88 mL (0.96 g, 6.1 mmol) of diethyl chlorophosphite was added, and 2.8 mL (3.2 g, 93 mmol) of aqueous hydrogen peroxide (concentration: 35%) was further added and stirred for 1.5 hours to synthesize 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(heptane-1,1-diphosphonic acid tetraisopropyl-1-diethyl phosphonate).

[0594] The volatile solvent (THF) was evaporated by rotary evaporation. After extraction by liquid separation, the solvent used in the liquid separation was removed by rotary evaporation. Further, unreacted diethyl chlorophosphite and by-products were removed by vacuum distillation.

[0595] The resulting liquid was separated and purified by passing it through a silica gel column to obtain 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(heptane-1,1-diphosphonic acid tetraisopropyl-1-diethyl phosphonate). Ethyl acetate, methanol, and propanol were used as developing solvents.

[0596] The liquid obtained after purification was dissolved in deuterated chloroform. １ 36 shows the solid line of 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(heptane-1,1-diphosphonic acid tetraisopropyl-1-diethyl phosphonate). １ The H-NMR spectrum is shown.

[0597] The peak at 2.1 ppm derived from the methine group protons adjacent to the two phosphorus atoms, which was observed in 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate), disappeared.

[0598] Furthermore, a peak derived from the proton (j) of the methine group adjacent to the oxygen atom of four diisopropyl phosphonate units was observed at around 4.7 to 4.9 ppm, and a peak derived from the proton (k) of the methyl group adjacent thereto was observed at around 1.3 ppm. Also, a peak derived from the proton (l) of the methylene group adjacent to the oxygen atom of two diethyl phosphonate units was observed at around 4.1 to 4.3 ppm, and a peak derived from the proton (m) of the methyl group adjacent thereto was observed at around 1.3 ppm. From these facts, it was confirmed that 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(heptane-1,1-diphosphonic acid tetraisopropyl-1-diethyl phosphonate) was obtained.

[0599] The peak at 7.27 ppm is due to chloroform, and the peak at 3.5 ppm is due to methanol.

[0600]

[0601] INDUSTRIAL APPLICABILITY The polymer or block polymer (polymer electrolyte membrane) of the present invention is (1) useful as an electrolyte membrane for a fuel cell in the production of a fuel cell, (2) useful as an anhydrous electrolyte membrane, and (3) useful as an ion exchange membrane in the production of an ion exchange device.

Claims

1. A monomer having a functional group via a spacer structure and capable of constituting a polymer, wherein the functional group is a phosphonic acid group and / or a phosphonic acid ester unit; a basic functional group; or a cationic functional group based on a basic functional group; and the spacer structure does not contain a functional group that is highly hydrolyzable, and each spacer structure has two or more of the phosphonic acid group and / or phosphonic acid ester units; one or more of the basic functional groups; or one or more of the cationic functional groups based on the basic functional group.

2. The monomer according to claim 1, having the functional group at the end of the spacer structure.

3. The monomer according to claim 1, wherein when the functional group is a phosphonic acid group and / or a phosphonate ester unit, the spacer structure is a linear, branched, or cyclic hydrocarbon spacer having 2 to 20 carbon atoms; when the functional group is a basic functional group, the spacer structure is a linear, branched, or cyclic hydrocarbon spacer having 3 to 20 carbon atoms; or when the functional group is a cationic functional group based on a basic functional group, the spacer structure is a linear, branched, or cyclic hydrocarbon spacer having 2 to 20 carbon atoms.

4. A polymer comprising a monomer unit consisting of the monomer according to claim 1, wherein the functional group of the monomer unit is a phosphonic acid group and / or a phosphonate ester unit, and the monomer unit has two or more of the phosphonic acid groups and / or phosphonate ester units per spacer structure; the functional group of the monomer unit is a basic functional group, and the monomer unit has one or more of the basic functional groups per spacer structure; or the monomer unit is not a fluorene-based monomer unit, and the functional group is a cationic functional group based on a basic functional group, and the monomer unit has one or more of the cationic functional groups based on a basic functional group per spacer structure.

5. The polymer of claim 4, wherein the polymer is a polymer formed by chain polymerization or a polymer formed by step-growth polymerization.

6. A block polymer in which at least an a block and a b block are linked by a covalent bond, the a block being the polymer described in claim 4, or containing a monomer unit consisting of a monomer having a functional group via a spacer structure and capable of constituting a polymer, the functional group of the monomer unit being a phosphonic acid group and / or a phosphonic acid ester unit, the spacer structure not containing a highly hydrolyzable functional group, and containing a monomer unit having one phosphonic acid group and / or one phosphonic acid ester unit per spacer structure, the b block being composed of a hydrophobic polymer or a water-repellent polymer, and being a polymer having a glass transition temperature (Tg) of 50°C or less.

7. The block polymer according to claim 6, wherein the b block is a polymer in which an alkyl chain is directly bonded to the main chain skeleton.

8. The block polymer according to claim 6 or 7, wherein the block polymer is a block polymer in which at least the a block, the b block, and the c block are linked by a covalent bond, and the c block is composed of a hydrophobic polymer or a water-repellent polymer, and is a polymer having a glass transition temperature (Tg) of 120°C or higher.

9. A polymer electrolyte membrane comprising the polymer according to claim 4 or 5, or the block polymer according to claim 6, 7, or 8.

10. The polymer electrolyte membrane according to claim 9, which is water resistant.

11. An ionomer or a membrane / electrode assembly comprising the polymer of claim 4 or 5, or the block polymer of claim 6, 7, or 8.

12. The ionomer or membrane / electrode assembly according to claim 11, which is water resistant.

13. A sheet-like material reinforced membrane comprising the polymer electrolyte membrane according to claim 9 or the ionomer according to claim 11, and reinforced with a sheet-like material having voids.

14. A sheet material-reinforced membrane according to claim 13, wherein the sheet material having voids is a nonwoven fabric and / or a porous sheet.

15. A fuel cell comprising an electrolyte membrane for a fuel cell, a water electrolysis device comprising an electrolyte membrane for water electrolysis, or an ion exchange device comprising an ion exchange membrane, which comprises the polymer according to claim 4 or 5, or the block polymer according to claim 6, 7, or 8.

16. A separation membrane, anion exchange membrane, or cation exchange membrane, comprising the polymer according to claim 4 or 5, or the block polymer according to claim 6, 7, or 8.

Images